The vast majority of Rhododendrons prefer well drained acidic soil with a PH between 4.5 and 6 with ample organic matter. Rhodos prefer their roots cool and benefit greatly from a deep organic mulch to retain the moisture an prevent the growth of weeds without mechanical damage to the shallow roots.
If in areas where alkaline soil is the norm; Rhododendrons can always be grown in raised beds using a mixture of topsoil and peat moss. In much of the eastern U.S. the soil is acidic but soil testing can is easily done to make sure.
Rhododendrons planted on limey alkaline soil are generally chlorotic meaning undersized yellowing leaves and loss of vigor.
Most Rhododendrons with large foliage prefer partial to full shade however there are exceptions which are noted in the text beneath including some which prefer full sun.
Generally it is a safe bet to expect Rhodos to thrive in a woodland understory where they enjoy protection from wind, late frosts and hot summer sun. Rhododendrons co-exist well with Oaks however shallow rooted Maples may be too much competition for most Rhodos.
All Rhododendrons suffer from prolonged periods of 100+ F in full sun.
All Rhododendrons prefer daytime temperatures under 80 F though many can tolerate more. During excessively hot weather the plants can be sprayed with water to cool the foliage however generally this is a practice I discourage generally in horticulture due that it can increase foliar funguses that are already present.
Generally Rhododendrons that are native to the Himalayas and high mountains in western China and northeast Burma; thrive in the Pacific Northwest and western Europe, especially in the British Isles. Rhododendrons native to eastern China, Japan, Korea, eastern Siberia, eastern Europe, the Caucasus and eastern North America; are more likely to thrive the more hotter humid summers of eastern North America.
Rhododendrons are generally not bothered by insect pests however in the case that they do get attacked by thrips, mites and vine weevils, they can be treated by a systemic insecticide.
Diseases aren't generally a problem when grown in ideal conditions however root rot can be a problem on soil that isn't properly drained. Planting too deeply will result in yellow foliage and often the smothering and death of the plant.
Rhododendrons can be fed with slow release fertilizer during spring to improve vigor.
Alkaline fertilizers such as blood, fish and bone meal should be avoided.
Rhododendrons should also not be fed with fast acting high nitrogen fertilizers. They are sensitive to high levels of fertilizer salts, causing "fertilizer burn" on overfed plants.
Most prunings dislike excessive pruning so pruning should be kept to shortening over extended branches, dead and diseased wood. Pruning is best done in spring. Old spent flower clusters can also be cut off to redirect the plants energy into foliage production and more growth.
Semi-ripe cuttings and layering during summer are the typical methods of propagation. When available, seed works too, though you will definately have more variability with the plants that result.Cuttings taken in mid summer during early morning and should be 3 to 4 inches in length with 3 to 4 leaves retained ( cut larger leaves in half to prevent excess transpiration ).
Seeds should be grown from flowers that are hand pollinated to make sure they turn out "pure bred". They can be sown in pans containing well drained, moist peat and bottom heat from 65 to 70 F. Germination is usually around 10 to 20 days.
Rhododendron aberconwayii
A upright, medium size evergreen shrub, native to northern Yunnan & Guizhou Provinces in southwestern China. Some records include: 10 years - 10 x 10 feet; largest on record - 10 x 10 feet.
The hard, thick, heavily-textured, leathery, elliptical leaves, up to 3 x 1.5 inches in size, are thick, smooth glossy deep green.
The abundant, light rose-pink ( spotted purple ), saucer-shaped flowers, up to 3 inches in length, are borne in loose trusses of 6 to 12 during late spring.
Hardy zones 6 to 9. Tolerant of full sun.
Rhododendron adamsii ( Lake Baikal Rhododendron )
A very attractive, divaricate, small, evergreen shrub that is native to subalpine zones in the mountains around Lake Baikal in Siberia as well as in Kamchatka.
The elliptic or oblong leaves, up to 0.8 x 0.3 inches in size, are dull deep green above, tan-brown beneath.
The leaves are known to contain hallucinogens that change perception of colors. Health effects of long term use are not known.
The pink flowers, up to 0.6 inches wide, are borne on dense clusters of 7 to 15 during early summer.
Hardy zones 3 to 6, it is very cold resistant however due to its requirement of continental climates and hatred of hot summers it is generally not suited for most gardens.
* excellent photo links
http://molbiol.ru/pictures/229254.html
http://byrranga.ru/ericaceae/rhododendron_adamsii/index.htm
Rhododendron aganniphum
A compact, rounded, medium-sized, evergreen shrub, native to southwest China. Some records include: 10 years - 6.6 feet; largest on record - 13 ( rarely over 10 ) feet.
The thick leathery, oblong leaves, up to 5 x 2.4 inches in size, are matte green above, whitish-yellow hairy beneath.
The white ( with rose-pink flushing ), funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 8 to 12 during late spring.
Hardy zones 7 to 9 ( seed source from southern Qinghai Province should be tested in zone 5 ).
Rhododendron arboreum
A slow growing, long lived, medium-size, evergreen tree to 60 feet or more, native to forests of the Himalayas ( from Kashmir to northern India to southern Tibet; south to northern India to Nepal to northern Burma & Vietnam ). Some records include: 10 years - 20 feet; largest on record - 100+ x 80 feet with a trunk diameter of 5.5 feet. It can sucker heavily if cut. It has already reached over 70 feet in the British Isles.
The wrinkled, leathery, oblong leaves, up to 12 x 3 inches, are smooth glossy deep green above; white or brown felted beneath.
The pink to scarlet-red, narrow, bell-shaped flowers, up to 2 x 2 inches, are borne in dense trusses of 15 to 20 during early to mid spring.
The attractive, red-brown bark is rough and peeling.
Hardy zones 7 to 9 tolerating as low as -5 F, preferring a site sheltered from excessive wind ( typical forest understory conditions ). Despite it's appearance, it is among the most heat and drought tolerant of the Rhodos. Very easy to grow, it is also more wind tolerant ( though less vigorous on open sites ) and less prone to insects and diseases than other Rhodos.
* historical archive photos
'Blood Red'
Intense-red flowers.
subsp. cinnamomeum 'Album'
Flowers are white with red spotting inside ( deep pink in regular subsp. cinnamomum ). The leaves are deep green above and rusty-orange woolly beneath.
Hardier north into zone 6.
Rhododendron argyrophyllum
A dense, upright, rounded evergreen large shrub to small tree, native to southwestern China. Some records include: 10 years - 23 feet; largest on record - 40 x 15 feet.
The deeply-veined, narrow elliptic leaves are up to 8 x 1.5 inches in size. The leathery foliage is glossy deep green above, silvery-white thinly-hairy beneath.
The white to light pink ( with purple spotting ), bell-shaped flowers, up to 2 inches in length, are borne in loose trusses of 6 to 12 during late spring.
The young shoots are silvery.
Hardy zones 6 to 9 preferring protection from excessive winter winds ( typical woodland understory conditions are good ).
'Heane Wood'
White flowers with purple spotting.
Rhododendron asterochnoum
A medium-sized evergreen tree, native to mountains of central Sichuan province in China where it often forms the understory in coniferous forest. It is closely related to Rhodo. calophytum.
Some records include: 10 years - feet; largest on record - 50 feet.
The leathery, oblong leaves, up to 10.5 x 3.5 ( rarely over 6 x 2.5 ) inches, are green above, woolly white to fawn-brown beneath.
The young foliage has a frosted appearance due to the whitish-gray hairs at the leaf margins.
The white to pinkish-red ( blotched deep-red at the base ), funnel-shaped flowers, up to inches in length, are borne in trusses of 15 to 20 during
The young stems are woolly white to fawn-brown.
Hardy zones 6 to 8, thriving especially well in the Pacific Northwest. Prefers a woodland understory environment. Not generally prone to diseases incl. Powdery Mildew.
Rhododendron arizelum
A rounded, spreading, evergreen large shrub to small tree, native to the from northeast India to southwestern China and northeast Burma.
Similar to Rhododendron fictolacteum except with wider leaves and pink or yellow flowers. It is slow growing but very long lived, up to 300 years.
Some records include: 10 years - 5 x 5 feet; largest on record - 25 x 25 feet.
The leathery, oval leaves, up to 14 x 5 inches, are deep green above, fawn-brown felted beneath.
The yellow ( rarely white or pink ) bell-shaped flowers, up to 1.5 inches in length, are borne in large trusses of 12 to 25 during mid spring.
The attractive flaking bark is brown.
Hardy zones 7 to 9
Rhododendron augustinii ( Augustine Rhododendron )
A fast growing, elegant, upright, bushy evergreen large shrub to small tree, native from southwestern to central China. Some records include: 10 years - 10 feet; 20 years - 15 x 12 feet; largest on record - 33 x 20 feet.
The elliptic leaves, up to 5 x 1.7 inches, are smooth deep green above, golden-brown beneath.
The very profuse, intense violet-blue ( spotted green ), broad funnel-shaped flowers, up to 2 inches in length, are borne in trusses of 2 to 6 during mid spring.
The young shoots are finely hairy.
Hardy zones 6 to 9 ( with hardiest clones tolerating -15 F ) preferring light shade and protection from excessive wind.
'Hardyi'
Pure white flowers.
Rhododendron auriculatum
A fast growing, bushy, spreading, evergreen large shrub or small tree, that is native to central China. Some records include: 10 years - 10 feet; 20 years - 30 x 20 feet; largest on record - 45 x 20 feet with a trunk diameter of 15 inches. A large tree grows at Henry Foundation in Gladwyne, Pennsylvania ( near Philly ).
The oblong leaves are up to 13 x 5 inches in size. The foliage is silvery hairy at first, turning deep green above, paler and hairy beneath.
The very fragrant, white to pink, funnel-shaped flowers, up to 4 inches in length, are borne in large trusses of 7 to 15 during MID SUMMER ( very unusual for temperate climate Rhodos ).
Hardy zones 7 to 9 tolerating as low as -5 F. Heat tolerant and thrives especially well in milder parts of the Mid Atlantic. It does prefer to grow in moist woodland conditions.
Rhododendron aurigeranum
A tall, upright, evergreen shrub, reaching a maximum height of 8 feet, that is native to New Guinea.
This is one of the tropical Vireya Rhododendrons.
The oblong, deep green leaves, up to 4 inches, are borne in whorls of 5.
The orange, funnel-shaped flowers, up to 3 inches in length, are borne in very showy trusses of 8 to 10.
Hardy zones 10 to 11
Rhododendron barbatum
A spreading, evergreen small tree, that is native to high mountain forests of northeast India, Nepal, southern Tibet and Bhutan. Some records include: 10 years - 17 feet; 20 years - 40 x 33 feet; largest on record - 60 x 40 feet with a trunk diameter of 14 inches.
The leathery, oblong leaves, up to 8 x 3.5 inches, are glossy deep green above, pale green beneath.
The intense scarlet-red, narrow bell-shaped flowers, up to 3 inches in length, are borne in rounded trusses of up to 20 during early spring.
The shoots are bristly and the bark is red-purple and peeling.
Hardy zones 6 to 8, preferring a sheltered woodland environment.
Rhododendron beanianum
A compact, upright, medium-sized, evergreen shrub, reaching a maximum height of 10 feet, that is native to high mountains of northeast India, southeast Tibet and northeast Burma. Some records include: 10 years - 6.5 feet.
The leathery, obovate leaves, up to 4 x 1.6 inches in size, are deep green above, rusty-orange downy beneath.
The intense deep red, funnel-shaped flowers are borne in trusses during mid spring.
Hardy zones 7 to 9.
Rhododendron beesianum
A rare small tree native to coniferous forests in the mountains of southwestern China and northeast Burma. It reaches up to 10 feet in 10 years and an eventual maximum height of 30 feet.
The leathery, oblong leaves, up to 14 x 4 inches in size, are deep green.
The white to pale rose flowers are borne in dense trusses during late spring.
Generally thought to be hardy north to zone 8, tolerating as low as 5 F; however selections from higher altitudes are likely hardy north into zone 6.
Easy to grow from seed however needs cool summers and excellent drainage.
Rhododendron brachyanthum
A dense, evergreen shrub, reaching up to 6.5 feet in 10 years, that is native to high mountains in southeast Tibet, Yunnan Province in China and northeast Burma.
The very aromatic, leathery, oblong leaves, up to 2.5 x 1 inch in size, are glossy deep green above, blue-green beneath.
The semi-pendulous, pale yellow flowers are borne late spring to early summer.
Hardy zones 4b to 8, tolerating as low as -25 F. Heat tolerant.
Rhododendron brachycarpum
Also called Rhodo. faureie. A dense, large, evergreen shrub native to Korea and northern Japan. Some records include: 10 years - 10 x 10 feet ( typically half that ); 23 years - 11 x 12 feet; largest on record - 18 feet. It is often dwarfed in the wild as it is often found in high mountains above the tree-line in its native range.
The leaves are up to 10 x 3.7 ( rarely over 7 ) inches in size. The attractive, tropical looking foliage is bronzy-bright green at first, turning to glossy deep green above, gray to fawn-brown hairy beneath.
The creamy-white ( with green spotting ) flowers, up to 1.5 inches in length, are borne in trusses of 8 to 20 during late spring.
Hardy zone 4b to 9, tolerating as low as -25 F. Does not like full sun.
* historic archive photo
'Tigerstedtii'
Also known as 'Peter Tigerstedt'. A vigorous clone from North Korea hardy north to zone 3 and can tolerate as low as -50 F! It even thrives in south-central and southeastern Alaska.
Otherwise similar except for the foliage which is extremely dark green.
Rhododendron brookeranum
An attractive, vigorous, evergreen large shrub, reaching a maximum height of 15 feet, that is native to Borneo. This is one of the tropical Vireya Rhododendrons.
The leaves, up to 10 inches in length, are green.
The fragrant, golden-yellow, orange or red ( whitish to creamy center ), funnel-shaped flowers, up to 3 inches in length, are borne in loose trusses of 5 to 14 during winter.
Hardy zones 10 to 11.
Rhododendron bureavii ( Bureau Rhododendron )
A beautiful, large evergreen shrub, native to Yunnan Province in southwest China. Some records include: 10 years - 13 x 8 feet; largest on record - 25 x 10 feet.
The elliptical leaves, up to 8 x 3 inches, are deep green above, woolly rusty-red beneath.
The white ( with deep red markings ), bell-shaped flowers, up to 2 inches in length, are borne in trusses of 10 to 15 during mid-spring.
The young stems are rusty-red felted.
Hardy zones 5 to 9, preferring shade and protection from excessive wind ( typical forest understory conditions ). Also requires excellent drainage.
'Ardrishaig'
Light pink flowers with deeper pink flushing and red spots.
Rhododendron burmanicum
A compact small evergreen shrub, native to the foothills of Mt. Victoria in Burma. Some records include: 10 years - 4 feet; largest on record - 8 x 8 feet.
The leaves, up to 3 inches, are scaly deep-green.
The profuse, yellow, funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 4 to 10 during mid spring.
Hardy zones 9 to 10 tolerating as low as 15 F. In the U.S. it only thrives in coastal California around San Francisco.
Rhododendron callimorphum
A rounded, medium- sized, evergreen shrub, native from western Yunnan Province in southwestern China to northeast Burma. Some records include: 10 years - 8 x 8 feet; largest on record - 11 x 10 feet.
The leathery, rounded leaves, up to 3 x 2 inches, are glossy deep gray-green.
The white, pink to rosey-pink, bell-shaped flowers, up to 2 inches in length, are borne in loose trusses of 5 to 8 during late spring.
Hardy zones 5 to 9 preferring a site protected from excessive wind.
Rhododendron calophytum
A very beautiful, evergreen, medium-sized tree, native to central China. Some records include: 10 years - 17 feet; largest on record - 65 x 30 feet with a trunk diameter of 2.2 feet.
The very large, deeply-veined, lance-shape to oblong leaves, up to 16 x 5 inches in size, are smooth glossy deep green above, paler beneath. The foliage droops and curls in cold weather.
The fragrant, white to pinkish-white ( spotted and basal blotched purple ), bell-shaped flowers, up to 3 inches in length, are borne in huge trusses ( up to 8 inches across ) of up to 20 during early to mid spring.
Hardy zones 6 to 8 tolerating as low as -15 F. It is the hardiest of the Rhodos with very large leaves, thriving especially well in the Pacific Northwest.
'Dominik'
Slightly hardier than the species ( possibly 5b ), this is the best hardy Rhododendron for tropical effect in cold climates.
* photos taken by Milan Havlis, owner of central Europe's premier plant nursery
Rhododendron calostrotum
A compact, low growing evergreen shrub, rarely reaching over 2 feet, that is native to the Himalayas ( from India to southern Tibet and Yunnan Province in China; south to northeast Burma ). Some records include: 10 years - 4 x 4 feet ( rarely over 2 feet in height ); largest on record - 5 x 4 feet.
The oblong to rounded leaves, up to 1.5 x 0.6 inches in size, are glossy silvery blue-green to deep green above, felted fawn-brown beneath.
The abundant, rose-red to pinkish-purple ( with darker spotting ), saucer-shaped flowers, up to 1 inches in length, are borne in trusses of 2 to 5 during late spring.
Hardy zones 5 to 9, prefers full sun on well drained soil.
'Gigha'
Compact in habit with profuse pink-red flowers.
Rhododendron caloxanthum
A evergreen large shrub, native to Burma.
Some records include: 10 years - 5 x 6.5 feet; largest on record - feet.
The rounded leaves, up to 3 inches, are deep green.
The abundant, bright orange-yellow, bell-shaped flowers, up to inches in length, are borne in trusses of 4 to 9 during mid to late spring. The flowers are scarlet-red in bud.
Hardy zones 7 to 9 preferring woodland understory conditions.
Rhododendron campanulatum
A bushy, evergreen large shrub to small tree, that is a widespread native to the Himalayas ( from Kashmir to southern Tibet; south to Nepal to Bhutan ). Some records include: 10 years - 10 feet; largest on record - 35 x 20 feet with a trunk diameter of 1.5 feet.
The leathery, oval leaves, up to 7 x 3.5 inches, are smooth deep green above, fawn-brown felted beneath.
The leaves droop and curl in cold weather.
The white or lavender-blue ( spotted purple ), bell-shaped flowers, up to 2 inches across, are borne in trusses of 8 to 12 during mid spring.
Hardy zones 5 to 8. On ideal sites, it may self seed freely.
'Auruginosum'
Foliage is blue-green at first.
Rhododendron campylocarpum
A compact, rounded to spreading, evergreen, large shrub to small tree, native to the Himalayas ( from northeast India to southwestern China and northeast Burma ). Some records include: 10 years - 6.5 feet; largest on record - 20 x 13 feet.
The attractive, elliptical to rounded leaves, up to 4 x 2.3 inches, are smooth glossy deep green above, whitish beneath.
The yellow, bell-shaped flowers, up to 3 inches in length, are borne in trusses of 6 to 10 during mid spring.
Hardy zones 5 to 9, requires excellent drainage.
* historical archive photos
Rhododendron campylogynum
A dense, very small, spreading, miniature, evergreen shrub, rarely reaching over 2 feet in height, that is native from eastern India to southwest China and northeast Burma. Some records include: 10 years - 20 x 20 inches; largest on record - 6 x 3 feet. Excellent for rock gardens.
The aromatic, leathery, obovate leaves, up to 1.5 x 0.7 inches, are glossy deep green above, silvery-white beneath.
The nodding, creamy-white, nodding, broad bell-shaped flowers, up to 1 inches in length, are borne in small trusses of 1 to 3 during late spring.
Hardy zones 5 to 9, requires consistantly moist soil.
'Celsum'
Larger growing, reaching up to 6.5 feet.
Rhododendron carneum
A evergreen large shrub, reaching a maximum size of 6 x 6 feet, that is native to the mountains of Burma.
The leaves, up to 8 inches, are glossy deep green above, scaly bluish beneath.
The fragrant, pink, tubular-shaped flowers are borne in trusses of 4 or 5 during early spring.
Hardy zones 8 to 10
Rhododendron carolinianum ( Carolina Rhododendron )
An attractive, very vigorous, compact, upright, medium-sized, evergreen shrub, native to the southeastern U.S. ( Tennessee to North Carolina; south to far northern Florida ). Some records include: fastest recorded growth rate - 2 feet; 10 years - 6.5 x 4 feet; largest on record - 10 x 14.5 feet with a trunk diameter of 1.5 inches.
The oval leaves, up to 3.5 x 1.7 inches, are glossy green.
The abundant, pink to rosey-purple, funnel-shaped flowers, up to 1 inch in length, are borne in loose trusses of 4 to 10 during late spring.
Hardy zones 4 to 9 in sun or shade on well drained soil. Rarely bothered by pests or disease.
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
'Album'
White flowers.
Rhododendron catawbiensis ( Catawba Rhododendron )
A vigorous, rounded, dense, spreading evergreen large shrub to small tree, typically maturing at 12 or more feet, that is native to the eastern U.S. ( from central Tennessee to eastern Kentucky to far western Maryland to central Virginia; south to northeast Alabama to northern Georgia to western South Carolina to central North Carolina ). Some records include: fastest recorded growth rate - 2 feet; 5 years - 12 feet ( record ); 10 years - 10 x 10 feet ( average ); largest on record - 27 x 27 feet with a trunk diameter of 0.5 feet. It is closely related and very similar to Rhodo. ponticum. It is long-lived, persisting up to 80 years or more.
The obovate leaves, up to 8 x 2 inches, are glossy deep green above, light green beneath.
The lilac-purple, funnel-shaped flowers, up to 2 inches in length, are borne in showy dense large trusses ( up to 6 inches across ) of 15 to 20 over a 2 week period during late spring.
Hardy zones 4 to 8 tolerating as low as -30 F. The flower buds are hardy to -25 F but the roots are only hardy to 0 F so mulching is recommended during winter. Heat tolerant but is also one of the more cold tolerant Rhodos, surviving even in south-central and southeastern Alaska. It typically abundantly sets seed, so deadheading is recommended in redirect energy into increased foliage and growth.
* photos taken on January 2010 in Columbia, MD
* photo taken on April 6 2010 near Wilkes-Barre, PA
* photo taken on Aug 3 in Luzerne Co, PA
* photo of unknown internet source
* photos taken on Nov 25 2012 near Wilkes-Barre, PA
* photos taken on Apr 2014 near Wilkes-Barre, PA
* photos taken on Oct 14 2015 in Baltimore Co., MD
* historic archive photos
* historic archive photo of multiple cultivars
'Album'
Glossy mid-green foliage and flowers that are lilac-pink in bud, opening to pure white.
Same size as R. catawbiense and vigorous in habit.
* photos taken on May 6 2010 @ Brookside Gardens, Wheaton, MD
* photos taken on May 13 2019 in Columbia, MD
'Blue Ensign'
Slower and shorter growing, reaching about 5 x 10 feet in 10 years, eventually more.
Flowers, up to 2.3 inches across, are lavender-blue blotched deep purple inside.
Not as cold hardy but heat tolerant for a Rhodo, zones 5b to 7.
'Boursault'
Very hardy with bright green leaves and intense lilac-purple flowers.
Same size as Rhodo. catawbiensis and vigorous in habit.
* photo taken on May 15 2011 in Columbia, MD
* photos taken on May 10 2012 in Columbia, MD
* photo taken on May 25 2014 in Columbia, MD
'English Roseum'
Bright lilac-pink flowers and deep green foliage.
Same size as R. catawbiensis and vigorous in habit.
Heat tolerant.
* photo taken on May 15 2011 in Columbia, MD
* photos taken on May 10 2012 in Columbia, MD
* photos taken on May 20 2014 in Columbia, MD
* photos taken on May 17 2017 in Columbia, MD
'Grandiflorum'
Dense and vigorous with light rose-purple flowers. Same size as R. catawbiensis.
* photos taken on Aug 22 2021 in Bayfield, ON
* photos taken on July 9 2022 in Bayfield, ON
'Nova Zembla'
A vigorous, medium-size evergreen shrub, reaching same size as R. catawbiensis..
The leaves, up to 8 inches in length, are deep green.
The intense red-purple flowers, funnel-shaped flowers are borne in dense, globular trusses during mid to late spring.
Hardy zones 3 to 8. Extremely hardy and also more heat tolerant than most Rhodies.
* photos taken on May 1 2010 in Howard County, MD
* photo taken on May 18 2011 in Columbia, MD
* photos taken on May 20 2014 in Columbia, MD
* photo taken on May 8 2015 in Elkridge, MD
* photo taken on May 20 2015 in Columbia, MD
* photo taken on May 26 2016 in Columbia, MD
* photos taken on May 25 2018 in Columbia, MD
'Purpureum Elegans'
A vigorous, compact, upright, medium-size evergreen shrub,
reaching the same size as R. catawbiensis.
The leaves are glossy mid-green.
The deep bluish-purple, funnel-shaped flowers are borne in dense, globular trusses during mid to late spring.
Hardy zones 3 to 8
* photo taken on May 20 2014 in Columbia, MD
* photos taken on May 4 2017 in Columbia, MD
* photo taken on May 28 2019 in Columbia, MD
'Roseum Elegans'
Very vigorous, reaching same size as R. catawbiensis. The flowers are rosy-lavender, and the foliage is deep green.
* photos taken on May 10 2012 in Columbia, MD
* photo taken on May 25 2014 in Columbia, MD
* photos taken on May 4 2017 in Columbia, MD
* photo taken on May 6 2017 in Columbia, MD
* photos taken on May 8 2019 Columbia, MD
* photos taken on May 11 2019 in Columbia, MD
'Roseum Pink'
Mid-pink flowers, otherwise identical to species.
* photo taken on annual Horticultural Society of Maryland Garden Tour
* photo taken on May 19 2011 in Bel Air, MD
* photos taken on May 10 2012 in Columbia, MD
* photo taken on May 25 2014 in Columbia, MD
* photos taken on May 13 2018 in Columbia, MD
* photos taken on May 6 2019 in Columbia, MD
* photos taken on May19 2020 in Columbia, MD
* photos taken on May 11 2021 in Columbia, MD
'Super Nova'
Similar to 'Nova Zembla' but this extremely attractive Rhodo is dense and compact, only reaching up to 4 x 4 feet in 10 years. It makes an excellent informal hedge.
* photo taken on May 15 2015 in Columbia, MD
Rhododendron caucasicum
A compact, medium-size, evergreen shrub, native to mountain slopes in western Russia, northern Turkey & the country of Georgia.
Some records include: 10 years - 3.5 x 4 feet; largest on record - 10 x 12 feet.
The oblong leaves, up to 5 x 1.5 inches, are smooth dull green above, fawn-brown felted beneath.
The white funnel-shaped flowers are borne in dense trusses of 6 to 15 during late spring.
Hardy zones 4 to 8, it does not tolerate extended drought.
PHARMACEUTICAL PROPERTIES: see http://www.webvitamins.com/Nutrient.aspx?id=2469
( I have not personally tested this product and therefore can not offer an opinion on its effectiveness ).
* historic archive photo
Rhododendron cephalanthum
A semi-prostrate to compact spreading, small evergreen shrub, native from western China into northern Burma. Some records include: 10 years - feet; largest on record - 5 x 4 ( rarely over 2.5 ) feet.
The aromatic, oblong leaves, up to 2 x 0.6 inches in length, are smooth green above, scaly beneath.
The profuse, white to pink, narrow tubular-shaped flowers, up to 0.7 inches in length, are borne in dense trusses of 8 during early spring.
The young shoots are densely bristled.
Hardy zones 7 to 9. Excellent for rock gardens but requires a site protected from excessive wind.
Rhododendron cerasinum
A evergreen large shrub, native to southeast Tibet and northeast Burma. Some records include: 10 years - 10 feet; largest on record - 20 feet.
The slightly curved, narrow, elliptical leaves, up to 4 x 1.7 inches, are smooth and green.
The intense-red, funnel-shaped flowers, up to 2 inches in length, are borne in trusses of 5 to 7 during late spring.
The attractive bark is orangish-brown in color.
Hardy zones 7 to 9
Rhododendron chapmanii ( Chapman's Rhodo )
Considered by some to be a subspecies of Rhodo. minus.
A rigidly upright, small evergreen shrub, native to sandy areas of northwest Florida where it is now endangered. Some records include: 10 years - 6 feet; largest on record - 10 x 10 feet.
The leathery, elliptical leaves, up to 2 inches in length, are deep green. The leaves are often curled at the edges.
The purplish-pink flowers are borne in trusses of 4 to 12 during late spring, sometimes repeating during mid-autumn in milder regions.
Hardy zones 7 to 9 ( 6 ) in full sun to partial shade. Underused in landscaping, it is among the best of all Rhododendrons for the hot humid southeastern U.S.
* photo taken on May 1 2010 @ U.S. National Arboretum, D.C.
* photos taken on Aug 24 2017 @ U.S. Botanic Garden, Wash. DC.
* photo taken by Mark A. Garland @ USDA-NRCS PLANTS Database
* historic archive photos
Rhododendron charitopes
A dense, low domed evergreen shrub that is native to mountains of southern Tibet, northwest Yunnan and northeast Burma. Some records include: 10 years - 2 feet; largest on record - 6.5 feet ( usually less than half that ).
The aromatic, leathery, obovate leaves, up to 3 x 1.5 inches, are glossy deep-green above, blue-white beneath.
The pink ( speckled deep-red ), funnel-shaped flowers are borne in trusses of 4 to 6 during mid spring, often repeating in autumn.
Hardy zones 6b to 8.
Rhododendron chrysanthum
Also called Rhododendron aureum. A small, evergreen shrub, reaching a maximum height of 3.5 feet, that is native to Mongolia, eastern Russia, northeast China and Korea.
The leathery, oblong leaves, up to 3.2 x 1.5 inches in size, are deep green.
The yellow, funnel-shaped flowers are borne in trusses of 5 to 8 during late spring.
Hardy zones 3 to 8.
Rhododendron ciliatum ( Ciliate Rhododendron )
A rounded, medium-size evergreen shrub, native to the Himalayas ( eastern Nepal, southern Tibet and Bhutan ). Some records include: 10 years - 5 x 6.5 feet; largest on record - 9 x 18 feet ( typically about half that ).
The leathery, oblong leaves, up to 4 x 2 inches, are glossy deep green and lightly bristled above.
The white to pale pink funnel-shaped flowers, up to 2 inches in length, are borne in small trusses of 2 to 4 during mid spring. The flowers are rosy-pink in bud.
The young shoots are bristly and the attractive bark is light brown and peeling.
Hardy zones 6b to 9. Prefers a site in partial shade and sheltered from excessive wind ( typical woodland understory ). Tolerant of alkaline soil!!!
Rhododendron cinnabarinum ( Cinnabar Rhodo )
A very attractive, compact to open upright evergreen large shrub, that is a widespread native from the Himalayas to northern Burma.
Some records include: 10 years - 10 x 8 feet; largest on record - 30 x 13 ( rarely over 20 ) feet.
It is a parent of many hybrid Rhododendrons.
The aromatic, leathery, broad oval to oblong leaves are up to 4.5 x 2 inches in size. The foliage is metallic gray-green above, red-brown felted beneath.
The deep orange to red, drooping, narrow tubular flowers, up to 2 inches in length, are borne in loose trusses of 3 to 9 during mid to late spring.
The shoots are purplish.
Hardy zones 7 to 9. It is unfortunately one of the few Rhododendrons that are prone to powdery mildew problems with the foliage.
'Blanfordii'
The very narrow flowers are red on the outside, yellow on the inside.
'Mount Everest'
Flowers are apricot orange on the outside, yellow on the inside.
'Purpurellum'
Intense plum-purple flowers.
'Xanthocodon'
Upright, reaching up to 13 feet in 10 years. The foliage is blue-green, turning to deep green. The flowers are golden-yellow.
Rhododendron concinnum ( Concinnum Rhodo )
A vigorous, upright, evergreen large shrub to small tree, native from southwestern to central China. Some records include: 10 years - 13 x 10 feet; largest on record - 20 x 12 feet.
The aromatic, elliptical leaves are up to 3.5 x 1.5 inches in size. The foliage is smooth deep blue-green above, scaly gray-brown beneath.
The abundant, rich blue-purple, broad funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 3 to 8 during mid to late spring.
Hardy zones 7 to 9 tolerating as low as -5 F, thriving as far north as Philly.
'Pseudoyanthinum'
Similar except for intense deep red to red-purple flowers.
Rhododendron crassum
Also called Rhododendron maddenii subsp. crassum. A evergreen, large shrub or small tree, native to the Himalayas ( from northern India to southern Tibet to Yunnan Province; south to northeast Burma, Thailand and northern Vietnam ). Some records include: largest on record - 27 x 17 feet.
The wrinkled, leathery leaves, up to 7 x 3 inches, are green above, scaly rusty-brown beneath.
The fragrant, creamy or pinkish-white, funnel-shaped flowers, up to 4 inches in length, are borne during early summer.
Hardy zones 8 to 9 preferring protection from excessive wind.
Rhododendron dalhousiae
A somewhat lax, upright, medium size evergreen shrub, native to the Himalayas ( from northern India to southern Tibet and Bhutan; south to Bangladesh ).
Some records include: 10 years - 8 x 6 feet; largest on record - 15 x 6 feet.
It is very similar in many ways to Rhodo. lindleyi.
The oblong leaves, up to 6 x 2 inches, are deep green.
The abundant, fragrant, light yellow fading to white, tubular flowers, up to 4.3 inches in length, are borne in trusses of 3 to 6 during late spring.
The young shoots are bristly.
Hardy zones 8b to 10 preferring a site with good protection from wind.
* historical archive photo
Rhododendron dauricum ( Dauricum Rhodo )
A medium-size, evergreen shrub, native to Mongolia, eastern Siberia, northern China to Japan. Some records include: fastest recorded growth rate - 2 feet; 10 years - 6.5 x 6 feet; 12 years - 8 feet; largest on record - 10 x 8 feet.
The aromatic, oval leaves, up to 1.7 x 0.7 inches in size, are densely-scaly. The foliage is glossy deep green above; rusty-brown hairy beneath. The foliage often turns attractive scarlet-red to purple-bronze during winter. In cold climates it may become deciduous during severe winters.
The pink to purple-pink, funnel-shaped flowers, up to 1.6 inches in length, are borne in pairs or singly during very early spring. There is also a form with white flowers and another form called 'Midwinter' with red-purple flowers.
Hardy zones 3 to 8 tolerating as low as -30 F. It is one of the very good Rhododendrons for use in the upper Midwest.
* photos taken on March 28 2010 @ U.S. National Arboretum, D.C.
* photo taken on Apr 10 2014 in Clarksville, MD
* photo taken on June 23 2013 @ U.S. National Arboretum, Washington, DC
* photos taken on Apr 17 2016 @ U.S. National Arboretum, DC
* photos taken on Mar 26 2021 @ U.S. National Arboretum, Wash, D.C.
Rhododendron davidsonianum ( Davidsonian Rhodo )
A open, upright, evergreen large shrub, native to Sichuan Province in China. Some records include: 10 years - 10 feet ( 6.5 feet is average ); largest on record - 20 x 13 feet.
The aromatic, lance-shaped leaves, up to 3 x 1 inches, are glossy deep green above, dull brown scaly beneath.
The abundant, white to whitish-pink, funnel-shaped flowers, up to 2 inches in length, are borne in trusses of 2 to 6 during early to mid spring.
Hardy zones 7 to 8 tolerating as low as 0 F
'Pink Form'
Pink flowers with deeper spotting.
Rhododendron decorum
A beautiful, vigorous, evergreen, small tree, native from southwestern China to northeast Burma and Laos. Some records include: 10 years - 20 feet ( typically about half that ); largest on record - 33 x 13 feet with a trunk diameter of 20 inches.
The leathery, oblong leaves, up to 12 x 4.5 ( rarely over 8 x 3 ) inches, are smooth deep green above, blue-green beneath.
The fragrant, white to light-pink, funnel-shaped flowers, up to 3 x 3.5 inches, are borne in trusses of 8 to 14 during late spring.
Hardy zones 4 to 9 and easy to grow. It often self seeds when grown in ideal conditions.
subsp. 'Diaprepes'
Larger glossier leaves, up to 12 inches in length. Larger flowers, up to 4 inches across, borne in huge loose trusses.
Rhododendron degronianum
A compact, rounded, spreading, medium-sized, evergreen shrub, native to central and southern Japan. Some records include: largest on record - 12 x 22 feet.
The deeply-veined leaves, up to 8 x 2 inches, are glossy deep green above, felted fawn-brown beneath.
The abundant, pink to red-pink, bell-shaped flowers, up to 2.5 inches in length, are borne in trusses of 6 to 15 during mid to late spring.
The stems are hairy white.
Hardy zones 6 to 9. Easy to grow.
Rhododendron denundatum
A vigorous, small, evergreen tree, native to high mountains ( close to tree-line ) in southwestern China. Some records include: largest on record - 30 feet.
The attractive, bullate, elliptical leaves, up to 6.5 x 2 inches, are silvery-white, turning to green above, white felted beneath.
The abundant, mid-pink ( spotted and blotched darker ), funnel-shaped flowers, up to 6 x 2 inches, are borne in trusses of 5 to 12 during late spring.
Hardy zones 6 to 8, thriving in the Pacific Northwest.
Rhododendron discolor ( Discolor Rhodo )
Considered by some to be a subspecies of Rhodo. fortunei.
An upright, evergreen large shrub to small tree, native from southwestern to central China. Some records include: 10 years - 17 feet; largest on record - 47 feet with a trunk diameter of 20 inches.
The oblanceolate leaves, up to 8 x 2.3 inches, are deep green above, pale green beneath.
The fragrant, white to very light-pink, funnel-shaped flowers, up to 4.5 inches in length, are borne in trusses of 5 to 12 during late spring.
Hardy zones 7 to 9 tolerating as low as -5 F
Rhododendron edgeworthii
A evergreen large shrub, native to the Himalayas ( from northern India to southwest China to northern Burma ). Some records include: 10 years - 8 x 8 feet; largest on record - 18 x 8 ( rarely over 11 ) feet.
The wrinkled, deeply-veined, oblong leaves, up to 7 x 2.5 inches, are glossy deep green above, brown hairy beneath.
The very fragrant, pure white ( with yellow basal blotch ) or pink with red flushing, broad funnel-shaped flowers, are borne in trusses ( up to 5 inches across ) of 2 to 3 ( rarely 4 ) during mid spring.
The felted shoots are tawny brown.
Hardy zones 7 to 10. Requires very well drained soil.
Rhododendron elliottii
A rare, upright, evergreen large shrub, native to northeast India.
Some records include: 10 years - 17 feet; largest on record - 25 feet
The leaves, up to 10 x 4 inches, are glossy green.
The intense scarlet-red, narrow bell-shaped flowers, are borne in trusses of 9 to 15 during early summer.
Hardy zones 8 to 10 tolerating as low as 10 F. Requires protection from severe frost.
Rhododendron facetum
A evergreen, small tree, closely related to Rhododendron elliotii, that is native Yunnan Province in western China, northeast Burma and northern Vietnam. Some records include: 10 years - 10 feet; largest on record - 40 x 8 feet
The oblong leaves, up to 8 x 3 inches, are glossy deep green.
The deep pink to scarlet-red, narrow bell-shaped flowers, are borne in trusses of 8 to 15 during mid summer.
Hardy zones 8 to 9 tolerating as low as 5 F.
Rhododendron falconeri ( Falconer Rhododendron )
A very handsome, stiff branched evergreen small tree, native to the Himalayas. Some records include: 10 years - 13 feet; 20 years - 40 x 20 feet; largest on record - 50 x 50 feet with a trunk diameter of 1.5 feet; longest lived - 80+ years.
The crinkled, large, oblong leaves are up to 14 x 6 or rarely 20 x 6 inches in size. The foliage is matt dark green above, woolly white to rusty-orange beneath.
The lightly fragrant, creamy-white to pink ( with purple blotch ) bell-shaped flowers, up to 3 inches in length, are borne in trusses of 12 to 25, up to 9 inches across, are borne mid to late spring over a long season.
The shoots are woolly.
The very attractive mottled to flaking bark is light gray, pink and red-brown in color. The trunk is similar in appearance to that of the Crape Myrtle.
Hardy zones 7 to 10 tolerating as low as 0 F on shaded sites with moist, well drained soil. They prefer a site protected from excessive wind and late spring frost.
subsp. 'eximeum'
Some records include: largest on record - 37 feet with a trunk diameter of 10 inches.
Foliage is rusty-brown beneath. Flowers are pink.
Rhododendron fargesii
Also called Rhododendron erubescens. Often considered to be a subspecies of Rhodo. oreodoxa.
A moderate growing, bushy, evergreen, large shrub that is native to central China. Some records include: fastest growth rate - 15 inches; 10 years - 13 x 13 feet; largest on record - 27 x 13 feet.
The leaves, up to 6 x 2.5 inches in size, are blue-green above, blue-white beneath.
The deep pink ( dotted in purple ), funnel shaped flowers, are borne in trusses of 10 to 12 during early spring.
Hardy zones 6a to 9 ( tolerating as low as -15 F ).
Rhododendron fastigiatum
A evergreen small shrub, rarely reaching up to 3 feet, that is native to the alpine zone of Yunnan Province in western China. Some records include: 10 years - 3.3 x 2 feet; largest on record - 5 x 3 feet
The scaly, very small, narrow leaves, up to 0.7 x 0.3 inches in size, are blue-green above, brown scaly beneath.
The blue-purple, funnel shaped, flowers, up to 0.5 inches in length, are borne in small trusses of 2 to 5 during mid spring.
The stems are dark brown.
Hardy zones 4 to 9
'Blue Steel'
Blue-green leaves and light violet flowers.
'Purple Gem'
* photo taken on April 10 2010 in Howard County, MD
Rhododendron ferrugineum ( Alpine Rhodo )
A dense, compact, rounded evergreen small shrub, native to the Pyrenees and the European Alps. Some records include: 10 years - 5 x 4 feet; largest on record - 6 x 5 feet
The bristly, elliptical leaves, up to 2 inches in length, are very deep green above, scaly rusty-brown beneath. The leaf margins are typically rolled over.
The profuse, deep pink to red-purple trumpet-shaped flowers, up to 1 inch in length, are borne in rounded trusses of 6 to 12 during late spring.
Hardy zones 4a to 8 in sun to partial shade. Prefers cool conditions.
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
'Album'
White flowers
'Coccineum'
Deep red flowers.
'Glenarn'
Deep rosey-pink flowers.
Rhododendron fictolacteum
Also called Rhododendron rex subsp. fictolacteum. A open, upright to rounded, evergreen small tree, native to the Himalayas ( from southwestern China to northeast Burma ). Some records include: 10 years - 13 feet; largest on record - 50 x 47 feet
The huge, oblong leaves, up to 13 x 5 inches, are glossy very deep green above, woolly red-brown beneath.
The white to pinkish-white ( with crimson blotch and spots ), bell-shaped flowers, up to 3 inches in length, are borne in large trusses of up to 25, during mid spring.
The shoots are woolly.
Hardy zones 6b to 8 tolerating as low as -10 F with no damage.
Rhododendron flinkii
Also called Rhododendron lanatum. A very beautiful, evergreen, large shrub, , reaching up to 10 feet, that is native to coniferous forests in high mountains from southeast Tibet to Bhutan. Some records include: 20 years - 6.5 feet.
The narrowly-elliptical leaves, up to 4.3 x 1.8 inches, are deep green above, glowing orange-brown beneath. The foliage is among the most handsome of all Rhodos.
The creamy-yellow ( spotted deep green ) funnel-shaped flowers, up to 1.8 inches in length, are borne in trusses of 5 to 10 during late spring
The leafstalks and young stems are woolly light brown.
Hardy zones 7 to 8 and is easy to grow in the Pacific Northwest. Being a native of alpine areas in the high Himalayas I would not expect this Rhodo to tolerate the hot humid summers of the eastern U.S. It prefers a woodland understory environment with cool, moist, well drained soil.
Rhododendron floribundum
An erect, small, evergreen tree, native to southwestern China. Some records include: 10 years - 17 feet; largest on record - 50 x 10 feet
The leathery, oblanceolate leaves, up to 10 x 2 inches, are deep green above, densely woolly white beneath.
The abundant, bell-shaped, lavender-purple flowers, are borne in trusses of 8 to 12, during early spring.
Hardy zones 8 to 9 ( reports of 7 ), prefers a site protected from wind. Thrives especially well in the Pacific Northwest.
'Swinhoe'
Rosey-purple flowers with a dark red blotch.
Rhododendron formosum ( Formosum Rhodo )
A handsome, fast growing, evergreen small tree, that is native to the Himalayas. Some records include: 10 years - 4 feet; largest on record - 33 feet
The linear, willow-like leaves are up to 6 x 2 inches in size. The foliage is glossy green above, lightly scaly beneath.
The fragrant, white to pink, funnel shaped flowers, up to 2.5 inches in length, are borne in trusses of up to 12 during late spring.
Hardy zones 8 to 9 tolerating as low as 10 F. It requires a site protected from wind.
Rhododendron forrestii ( Forrest Rhododendron )
A small, creeping to spreading evergreen shrub, native to Tibet and Yunnan Province in China as well as northern Burma. Excellent for shady rock gardens and makes a great groundcover. Some records include: 10 years - 1 x 4 feet; largest on record - 3 x 5 feet. After many decades it may grow even wider due to its habit of self rooting.
The leathery, obovate or rounded leaves are up to 2 x 1.3 inches in size. The foliage is glossy rich deep green above, purplish beneath.
The large, scarlet-red, narrow bell-shaped flowers, up to 2 inches long, are borne singly or in pairs during mid spring.
Hardy zones 6 to 8 requiring a cool, moist climate.
Rhododendron fortunei ( Fortune's Rhododendron )
A vigorous, broadly upright to spreading, evergreen large shrub, reaching around 15 feet, that is a widespread native to eastern China. Some records include: fastest recorded growth rate - 2 feet; 10 years - 10 feet; largest on record - 40 x 27 feet.
The thick, leathery leaves, up to 8 x 3 or rarely 10 x 3.5 inches, are luxuriant deep green.
The leafstalks are red-purple.
The fragrant, pure white to pink funnel-shaped flowers, up to 4.5 inches in length, are borne in loose trusses of 6 to 12, are borne during late spring. A rare form exists with red flowers.
The rough bark is gray-brown.
Hardy zones 5 to 9 tolerating as low as -23 F. Heat tolerant if grown in shade.
Generally pest free and easy to grow.
* photos taken @ U.S. National Arboretum on Feb 2009
* photos taken @ Tyler Arboretum near Philly on August 2004
* photos taken on May 1 2010 @ U.S. National Arboretum, D.C.
* photo taken on May 8 2010 @ U.S. National Arboretum, D.C.
* photos taken on May 8 2010 @ McCrillis Gardens, Bethesda, MD
* photo taken on June 18 2013 in Columbia, MD
* photos taken on July 2013 in Columbia, MD
* photos taken on May 14 2019 in Ellicott City, MD
subsp. 'Discolor'
See Rhododendron discolor
Rhododendron fulgens
A very handsome, dense, large evergreen shrub, native to the Himalayas ( from northeast India to southern Tibet to Bhutan ). Some records include: 10 years - 10 feet; largest on record - 20 x 10 feet.
The obovate leaves, up to 4.5 x 2.8 inches, are gray-green, turning to glossy deep green above, fawn-felted beneath.
The funnel-shaped flowers are scarlet-red, borne during early spring.
The attractive bark is red-brown.
Hardy zones 7 to 9
Rhododendron fulvum
A shapely, rounded to spreading, evergreen small tree, native from southwestern China to northeast Burma, at elevations of 8000 to 14 000 feet.
Some records include: 10 years - 17 feet; largest on record - 40 x 17 feet with a trunk diameter of 1 foot.
The obovate leaves, up to 11 x 3.5 inches in size, often droop and curl in cold weather.
The very attractive foliage is smooth glossy deep green above, orange woolly beneath.
The abundant, pale to rose-pink ( with deep red basal blotch ) narrow bell-shaped flowers, up to 2 inches, are borne in dense rounded trusses of 3 to 20 during early spring.
The felted shoots are brownish-yellow.
Hardy zones 7 to 8 ( 5 I suspect may be possible but only with seed source from highest altitudes ), requires protection from excessive wind or late spring frosts. It often freely self seeds.
Rhododendron genestierianum
A rare, moderate to fast growing, slender, tall evergreen shrub, native to southwestern China and northern Burma. Some records include: 10 years - 3 feet; largest on record - 17 feet.
The narrow leaves, up to 6 x 1.7 inches, are smooth bright blue-green above, intensely blue-white woolly beneath.
The plum purple, hanging, tubular, bell-shaped flowers, up to 0.5 inches in length, are borne in trusses of 12, during mid spring.
The young stems are red-purple, and the older stems have peeling mahogany bark.
Hardy zones 8 to 9, preferring a site protected from wind.
Rhododendron x geraldii
A evergreen large shrub to small tree that is the naturally occuring hbyird between Rhodo praevernum & R. sutchuense. Some records include: 25 years - 10 x 12 feet; largest on record - 23 feet with a trunk diameter of 11 inches.
The long narrow leaves are deep green.
The mauve-pink funnel-shaped flowers, up to 3 x 4 inchesh, are borne in huge trusses ( up to 9 inches across ) of up to 13 during early spring.
Hardy zones 7 to 9, preferring a protected woodland environment.
Rhododendron giganteum
A vigorous evergreen medium size tree, native to western Yunnan Province in southwestern China. Some records include: 12 years - 6 feet; largest on record - 80 x 45 feet with a trunk diameter of 2.5 feet.
The leaves, up to 16 x 6 inches, are glossy deep green.
The rose-purple to deep red flowers, are borne in huge trusses of up to 25.
Hardy zones 8b to 9
Rhododendron glaucophyllum
A dense, compact, bushy, spreading evergreen small shrub, native from northern India to southeast Tibet & Bhutan. Some records include: 10 years - 5 x 5 feet; largest on record - 8 x 6 feet. A great plant for large rock gardens.
The aromatic, lance-shaped leaves, up to 3.5 x 1 inches, are glossy, deep green above; scaly bluish-white beneath.
The fragrant, pink to rose-red, bell-shaped flowers, up to 1 inch in length, are borne in trusses of 4 to 10, during mid to late spring.
The scaly shoots are red-brown. The attractive bark on the trunk is reddish-brown and peeling.
Hardy zones 6 to 9
Rhododendron glischrum
A moderate to fast growing, dense, upright, large evergreen shrub, native to mountains of southern Tibet and northeast Burma at elevations of 13000 to 14000 feet.
Some records include: 10 years - 10 feet; 15 years - 15 feet; largest on record - 27 x 10 feet.
The oblong leaves, up to 12 x 3 inches, are hairy deep green above, densely bristly beneath.
The white, pink or pink-purple ( with deep red blotch and spotting ) flowers, up to 1.5 inches in length, are borne in trusses of 10 to 15 during early spring.
The flower and leaf buds are sticky.
The rough bark is greenish-gray.
Hardy zones 7 to 9 tolerating as low as -5 F. If easily self seeds.
Rhododendron grande
A evergreen small tree, native to the Himalayas ( from northern India to southern Tibet to Bhutan ), where it is in many places a dominant tree at elevations of 8000 to 10 000 feet.
Some records include: 8 years - 6 x 4 feet; 10 years - feet; 40 years - 25 x 25 feet; largest on record - 50 x 25 feet with a trunk diameter of 1.5 feet.
The leaves, up to 36 x 10 inches, are
The creamy-white ( with a purple blotch ) flowers, up to 3 x 3 inches, are borne in trusses ( up to 7 inches across ) containing 20 to 25 blooms.
Blooming usually doesn't begin until the age of 12 but later blooms so profusely that it is always recommended to deadhead the old blooms to increase vigor.
Hardy zones 8 to 9, tolerates as low as 12 F with no damage. In the U.S., it grows best in the San Francisco Bay area, t also thrives especially well in parts of the British Isles. Prefers consistent moisture, partial shade and protection from wind.
'Pink Form'
Intense mid-pink flowers.
Rhododendron griersonianum
A evergreen open, lax medium sized shrub, native from western Yunnan Province in southwest China to northeast Burma. Some records include: 10 years - 8 x 8 feet; largest on record - 13 x 10 feet.
The narrow leaves, up to 9 x 3 inches, are olive green above, woolly pale brown beneath. The leaves are held for 2 years. The leaf buds are long and conical.
The scarlet-red ( deep red in bud ), trumpet-shaped flowers, up to 3 inches in length, are borne in trusses of 5 to 12 during early summer.
The young stems are woolly hairy later becoming bristly with winter buds that have long scales.
The attractive bark is rough and brown.
Hardy zones 7 to 9. Sun tolerant but needs protection from late spring frost and wind. Can be pruned easily. Easy to propagate from cuttings.
* photos taken on Nov 3 2013 in Columbia, MD
Rhododendron griffithianum
A evergreen stately, spreading, open small tree, native to the Himalayas ( from northern India to southeast Tibet and Bhutan ). Some records include: 10 years - 17 feet; largest on record - 60 x 25 feet with a trunk diameter of 1 foot.
The oblong leaves, up to 12 x 5 inches, are smooth mid-green.
The fragrant, white to pinkish-white, bell-shaped flowers, up to 3 inches in length, are borne in trusses of 3 to 6 during mid spring.
The attractive peeling bark is reddish-brown and gray.
Hardy zones 7 to 9 in partial to full shade in a position sheltered from wind and late spring frost.
'Deep Pink Form'
Deep pink flowers.
Rhododendron habrotrichum
A evergreen large shrub, that is native to western Yunnan Province in China to northeast Burma. Some records include: 10 years - 6.5 feet; largest on record - 20 feet with a trunk diameter of 11 inches.
The oval leaves, up to 5 x 1.6 inches in size, are matte deep green.
The pink flowers are borne during mid-spring.
The twigs and leafstalk are densely red-purple bristly.
Hardy zone 7 to 9
Rhododendron haematodes ( Haematodes Rhododendron )
A slow growing, compact, spreading, evergreen, medium-sized shrub, reaching up to 8 feet, that is native to Yunnan Province in western China. Some records include: 10 years - 6 x 5 feet; largest on record - 10 x 10 feet.
The leathery oblong leaves, up to 5.5 x 2 inches, are smooth deep green above, orange felted beneath.
The scarlet-red flowers, up to 2.3 inches in length, are borne in trusses of 6 to 10 during mid spring.
The woolly shoots are brown.
Hardy zones 7 to 9 tolerating as low as -5 F.
Rhododendron hanceanum
A compact, spreading, small evergreen shrub, typically only reaching around 1.5 feet in height, that is native to central Sichuan Province in central China. Some records include: 10 years - 4 x 4 feet; largest on record - 7 x 6 feet.
The lance-shaped leaves are up to 5 x 2.5 inches in size. The foliage is bronze at first, turning to deep green above, scaly pale-green beneath. The foliage turns purplish in winter.
The lightly fragrant, small, pale yellow, funnel-shaped flowers, up to 1 inch long, are borne in dense trusses of 5 to 15, during late spring.
The shoots are bronze.
Hardy zones 5 to 9. Great for containers and rock gardens.
Rhododendron hippophaeoides
An erect, suckering, dense, compact, evergreen small shrub, native to southwestern China. Some records include: 10 years - 5 x 5 feet; largest on record - 5.5 x 5 feet. It is an ideal plant for use in rock gardens.
The aromatic, narrow oblong leaves, up to 1.7 x 0.6 inches, are matte, light gray-green above, scaly grayish beneath.
The purplish-blue saucer-shaped flowers, up to 1 inches in length, are borne in tight trusses ( up to an inch wide ) of 6 to 9 during early to mid spring. It often repeat blooms in early fall.
Hardy zones 4 to 9 in full sun to partial shade. Tolerant of very moist soil however still requires drainage. It tolerates frost even while in flower.
'Hada Shan'
Taller growing, reaching up to 6.5 feet, with lavender-blue flowers.
Hardy to as low as -25 F.
Rhododendron hirsutum ( Hairy Alpen Rose )
A evergreen small shrub, native to mountains in south central Europe. Some records include: 10 years - 2 feet ( typically closer to 1 foot ); largest on record - 5 x 5 feet ( typically around 2 feet ).
The slightly bristle-edged leaves, up to 1.3 x 0.5 inches, are deep green above, scaly beneath.
The pink to scarlet-red tubular flowers, up to 0.7 inches in length, are borne in trusses of 5 to 8 during early summer.
The shoots are bristly.
Hardy zones 3 to 9. Lime tolerant.
* photo taken on August 3 2010 @ University of Guelph Arboretum, Ontario
Rhododendron hodginsonii ( Hodgeson Rhododendron )
A small evergreen tree, that is native to the Himalayas from northern India to southern Tibet. Some records include: 10 years - 5 feet; largest on record - 23 feet.
The very leathery, deeply veined, oblanceolate leaves are up to 12 x 4 inches in size. The foliage is glossy deep green above, silvery-white to brown felted beneath.
The peeling bark on mature trees is attractively mottled cream, pinkish and green.
The rose-red flowers, up to 2.3 inches in length, are borne in large clusters of 12 to 20, during early summer.
Hardy zones 8b to 9 tolerating as low as 10 F, requires partial shade. Prefers a site protected from excessive wind.
Rhododendron hyperythrum
A dense, compact, round to spreading evergreen medium-sized shrub to small tree, that is native to Taiwan. Some records include: 10 years - 5 x 4 feet; largest on record - 10 x 9 feet.
The very attractive, curled, elliptic leaves are up to 5 x 1.5 inches in size. The leathery foliage is deep green.
The pure white ( with red spots ), funnel-shaped flowers, up to 2 inches in length, are borne in loose trusses of up to 10, during mid to late spring. The flowers may sometimes be pink.
The young shoots are smooth.
Hardy zones 6 to 9 tolerating as low as -15 F if protected from excessive wind.
Heat and sun tolerant, it is among the few good Rhodos for the hot humid southeastern U.S..
Rhododendron impeditum
A very compact, dense, evergreen dwarf groundcover shrub, native to western China. Some records include: 10 years - 2 feet ( average is 8 inches ); largest on record - 4 x 5 ( rarely over 1.5 x 3 ) feet.
The aromatic, small, elliptical leaves, up to 0.7 x 0.3 inches in size, are glossy deep green above, rust-brown scaly beneath.
The abundant, light purple, funnel-shaped flowers, are borne in small trusses of 1 to 4 during mid-spring.
Hardy zones 4 to 8 tolerating as low as -30 F
* photo taken on Mar 22 2012 in Columbia, MD
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
Rhododendron imperator
A low prostrate to mat-forming, evergreen shrub that is excellent for use in rock gardens. Some records include: 10 years - 16 x 20 inches; largest on record - 3.3 feet. It is native to southeast Tibet and northeast Burma.
The aromatic, oblong leaves, up to 1 x 0.5 inches in size, are deep green.
The pinkish-purple, funnel-shaped flowers, up to 1.2 inches in length, are borne singly or in pairs during mid spring.
Hardy zones 7 to 9.
Rhododendron insigne
An attractive slow growing, dense, evergreen, large shrub, native to southern Sichuan Province in western China. Some records include: fastest recorded growth rate - 1.5 feet; 10 years - 6.5 x 6.5 feet; largest on record - 20 x 16 feet.
The leathery, obovate leaves, up to 5.5 x 1.8 inches in size, are glossy green above, bronze beneath.
The pale pink ( spotted deep-red ) bell-shaped flowers, up to 2 inches in length, are borne in round trusses of 8 to 16 during late spring.
Hardy zones 5 to 9. Tolerant of full sun.
Rhododendron irroratum
An erect evergreen large shrub to small tree, native to southwestern China and northern Vietnam at elevations of 9000 to 11 000 feet. Some records include: 10 years - 13 feet ( average closer to 5 feet ); largest on record - 30 x 12 feet.
The elliptic leaves, up to 6 x 1.7 inches, are matte mid-green. The leaves persist as long as 3 years.
The abundant, narrow, white ( rarely pinkish-purple ) bell-shaped flowers, up to 2 inches in length, are borne in trusses of 8 to 15 during early to mid spring. The flowers often have spots that can be either green, deep red or deep purple.
The bark is light brown.
Hardy zones 7 to 9, tolerating as low as 0 F. Easy to grown.
'Polka Dot'
The pink flowers are heavily spotted purple.
Rhododendron jasminiflorum ( Jasmine Flowered Rhodo )
A spreading evergreen small shrub, native to Malaysia, Sumatra and the Phillipines.
Some records include: largest on record - 8 x 6 feet.
It is sometimes used for hanging baskets. It is one of the Vireya Rhododendrons.
The elliptic leaves, up to 2.5 inches, are deep green.
The abundant, strongly fragrant, white ( with pink stamens ) tubular flowers, up to 2 inches in length, are borne in dense trusses of 6 to 12 during
Hardy zones 10 to 11. Resistant to pests and diseases and has been used in hybridizing tropical Rhodos.
Rhododendron javanicum
A vigorous spreading evergreen large shrub to small tree, , reaching up to 15 feet, that is native to Java and Sumatra in southeastern Asia. It is one of the Vireya Rhododendrons. It has been used extensively in the hybridizing of tropical Rhododendrons.
The leaves, up to 8 inches in length, are glossy green and scaly.
The leaves are borne in whorls of 5 to 8.
The intense orange funnel-shaped flowers, up to 2 inches in length, are borne in trusses of 4 to 20.
Hardy zones 10 to 11
Rhododendron johnstoneanum ( Johnston Rhododendron )
A spreading, large evergreen shrub, native to northern India. Some records include: 10 years - 4 feet; largest on record - 15 x 8 feet.
The hairy, elliptic leaves, up to 5.5 x 2 inches, are deep green.
The creamy-white funnel-shaped flowers, up to 3 inches in length, are borne in trusses of 3 to 5. The flowers have a yellow basal blotch and are often flushed purple or pink.
The attractive peeling bark is red-brown. The stems are bristly.
Hardy zones 7 to 9 preferring a site protected from excessive wind. Heat tolerant.
'Demi-John'
Flowers are white with yellow-green flushing.
'Double Diamond'
Double, light yellow flowers.
'Robeotinctum'
Flowers are striped white and pink.
Rhododendron kawakamii
A evergreen small shrub, reaching a maximum height of 5 feet, that is native to Taiwan at elevations of around 6500 to 7000 feet.
The thick, leathery, oblong leaves, up to 2 x 1.2 inches in size, are glossy green above, yellow-green beneath.
The white to yellow broad funnel-shaped flowers, up to 0.5 inches in length, are borne in trusses of 3 to 7 during
Hardy zones 8 to 11. Requires shelter from sweeping winter winds in climates where frost occurs.
Rhododendron keiskei ( Keisuki Rhododendron )
A very slow growing, evergreen small shrub, native central to southern Japan. Some records include: 10 years - 3 x 3 feet; largest on record - 13 x 13 feet.
The narrowly-elliptical leaves, up to 4 x 1.3 inches, are bronze at first, turning to hairy glossy deep green above, scaly pale green beneath. The foliage turns reddish during winter.
The creamy-yellow, broad funnel-shaped flowers, up to 1 inches in length, are borne in small trusses of 2 to 6 during mid-spring.
The older stems have peeling grayish-brown bark.
Hardy zones 4 to 8
'Prostrata'
The form typically found in cultivation which produces a low growing, creeping mat, almost never reaching above 1.5 feet. Some records include: 10 years - 1 x 3 feet; largest on record - 2 x 3 feet.
Rhododendron keleticum
A low, semi-prostrate evergreen shrub, native from southeastern Tibet to northeast Burma, that is similar to Rhododendron calostrotum except smaller in all its parts. Some records include: 10 years - 12 x 20 inches ( typically around 6 inches in height ); largest on record - 1 x 4 feet.
The leathery, elliptical leaves, up to 1.3 x 0.3 inches in size, are glossy deep-green above, brown scaly beneath.
The abundant, purple-red ( heavily spotted deep-red ), funnel-shaped flowers, up to 1.5 inches across, are borne in trusses of 2 or 3 during mid to late spring.
Hardy zones 6 to 8, tolerating as low as -15 F.
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
Rhododendron kesangiae ( Kesangiae Rhodo )
A evergreen large shrub to small tree, native to fir forests in the high elevations of mountains in Bhutan and nearby parts of India. It is among the most spectacular of all large foliaged Rhodos.
Some records include: 10 years - 13 feet; 20 years - 27 feet; largest on record - 40 feet.
The huge, heavily-elliptical to obovate, broad-elliptical, leaves, up to 12 x 6.5 inches, are green; silvery to fawn-brown woolly beneath. The very attractive emerging foliage is silvery-white.
The funnel-shaped pink to rose-pink ( with a large purple blotch ) flowers, up to 1.8 x 1.5 inches, are borne in dense trusses of 16 to 30 during mid spring. White and rich purple flowering forms have been found in its native range.
The rough bark is gray-brown.
Hardy zones 7 to 8 in partial to full shade. Native to the cool misty montane forests of the high Himalayas; this Rhodo only grows in the U.S. within the coastal rainforest zone on the west coast from Vancouver Island to north of San Francisco, CA. Within that range it becomes easy to grow, even on soil too wet for most Rhododendrons.
Rhododendron konori ( Konori Rhodo )
A very beautiful, evergreen medium-sized shrub, reaching a maximum size of 12 x 6 feet, that is native to New Guinia.
It is among the tropical Vireya Rhododendrons.
The leaves, up to 6 inches in length, are matte blue-green.
The very fragrant, very large pure white to pinkish,funnel-shaped orchid-like flowers, up to 6 inches in length, are borne in trusses of 5 to 8.
Hardy zones 10 to 11
Rhododendron lacteum ( Lacteum Rhodo )
A spectacular, upright, evergreen small tree, native to western Yunnan Province in China. Some records include: 10 years - 17 feet ( usually less than half that ); largest on record - 33 x 12 feet.
The deeply-veined, rounded leaves, up to 8 x 4 inches, are deep green above, brownish beneath.
The abundant, bright yellow, bell-shaped flowers, up to 2 inches in length, are borne in dense trusses ( up to 7 x 7 inches ) of 15 to 30 during late spring.
The very stout twigs are 0.5 inches thick.
Hardy zones 7 to 9 tolerating as low as -5 F. Requires a site protected from wind and very acidic soil.
Rhododendron laetum
A evergreen medium-size shrub, reaching a maximum size of 10 x 5 feet, that is native to northwest New Guinea.
This is one of the tropical Vireya Rhododendrons.
The elliptic leaves, up to 3.5 inches, are glossy deep green.
The golden-yellow broad funnel-shaped flowers, up to 3 inches in width, are borne in trusses of 6 to 8. The older flowers have orange to red shading.
Hardy zones 10 to 11
Rhododendron lanigerum
A evergreen small tree, native from northeast India to southeast Tibet.
Some records include: 10 years - 20 feet ( typically less than half that ); largest on record - 40 feet.
The deeply veined, smooth, wrinkled, oblanceolate leaves, up to 10 x 3 inches, are deep green above, white to fawn-brown woolly beneath.
The deep pink to pink-purple bell-shaped flowers, up to 1.5 inches in length, are borne in trusses of up to 27 during late spring,
Hardy zones 7 to 9
'Chapel Wood'
Very large trusses of rosey-pink flowers.
'Red Form'
Red flowers
'Round Wood'
Deep red flowers.
'Silvia'
Pale red flowers with white flushing ( also a deep red ring in the throat ).
'Stonehurst'
Large trusses of pale red flowers.
Rhododendron lapponicum ( Lapland Rosebay )
A rhizomatous, small, dense, evergreen shrub, reaching up to 2.6 ( rarely over 1.5 ) feet in height, that is native to sandy or gravelly beaches or tundra in subarctic regions of North America and Eurasia. In North America, it is found from far northern Alaska to far northern mainland Northwest Territories to central Nunavut to Labrador; south to northern British Columbia to far northern Wisconsin to far northern Ontario to high mountains in New York State as well as Mt Washington in New Hampshire and Mt Katahdin in Maine. In Ontario, it is abundant on the shores of Hudson Bay but extremely rare elsewhere. In Eurasia; it is found from Scandinavia to eastern Siberia; south to Mongolia, Manchuria, Korea and Japan. It is also native to Greenland. Some records include: largest on record - 3.3 x 4 feet. It is often reduced to a groundcover carpet in the windswept tundra where it commonly grows. Further south, it is usually found on moist, acid bogs and sandy shorelines.
The oblong to elliptical leaves are up to 1 x 0.3 ( rarely over 0.6 ) inches in size. The foliage is dull blue-green above; downy tawny-brown beneath; turning to red and purple during the winter.
The reddish to bright purple flowers, up to 0.6 inches long, are borne in clusters of 2 to 6 during early summer.
Hardy zones 2 to 5, thriving even in interior Alaska. This is the worlds hardiest Rhododendron.
* USDA-NRCS PLANTS Database
Rhododendron ledebourii
A very attractive, dense, medium-sized shrub, reaching up to 5 feet in 10 years, 8 feet in 20 years. Despite being semi-evergreen to evergreen, it is otherwise very similar to R. dauricum. It is native to the Altay and Sayan Mountain Ranges in Siberia. It is also native to Mongolia.
The leathery, oval or oblong leaves are up to 1.1 x 0.8 inches in size. The leaves are similar to that of Rhododendron 'PJM'.
the luxuriant mid-green foliage often turns to deep red during autumn, then finally to blackish-purple during winter.
The abundant, pale purplish-pink flowers, up to 1.8 inches wide, are borne in clusters of up to 8 from the axils of previous years leaves during mid-spring. Autumn rebloom often occurs however less profusely.
Hardy zones 4 to 7 ( 3 on protected sites ).
Rhododendron lepidostylum
A very attractive, vigorous, compact, mounding to spreading small evergreen shrub, native to western China.
Some records include: 10 years - 3.3 x 4 feet ( often much lower ); largest on record - 5 x 5 feet.
The bristly-edged, leathery, obovate leaves, up to 1.7 x 0.8 inches in size, are silvery-blue, turning blue-green above, golden scaly beneath. The leaf margins are rolled downwards.
The yellow, broad funnel-shaped flowers, up to 1 inches in length, are borne in trusses of 1 to 3 during late spring.
The young stems are intense blue-green.
Hardy zones 5 to 9. Easy to grow and propagate. Prefers protection from excessive wind.
Rhododendron leucaspis
A dense, compact, rounded small evergreen shrub, native to southern Tibet.
Some records include: 10 years - 2 x 3.3 feet; largest on record - 4 x 5 feet.
The bristly, broadly-elliptic leaves, up to 2.8 x 1.3 inches, are deep green.
The very wide bell-shaped, white ( with brown anthers ) flowers, up to 2.3 inches in length, are borne in small trusses ( up to 2 inches wide ) of 1 to 3 during late winter into early spring. The flowers are often tinged with pink as they age.
Hardy zones 7 to 9. Requires shelter from excessive wind.
Rhododendron lindleyi
A somewhat lax, medium-size evergreen shrub, native to the Himalayas.
Some records include: 10 years - 8 x 6 feet; largest on record - 17 x 6 feet.
The slightly wrinkled, thinly-leathery, narrow-elliptical leaves, up to 6 x 2.3 inches, are deep green.
The abundant, very fragrant, white ( with yellow blotch ) tubular flowers, up to 4.3 inches in length, are borne in trusses of 3 to 6 during late spring. The flowers are often tinged pink.
Hardy zones 8b to 10 preferring a site with good protection from wind.
This Rhodo can be cut back hard if necessary before growth begins.
Rhododendron lochiae ( Australian Rhododendron )
A slow growing, compact, bushy, medium size, evergreen shrub, native to the far northern tip of Australia.
Some records include: largest on record - 20 feet.
It is one of the tropical Vireya Rhododendrons.
The broad obovate leaves, up to 4 inches in length, are deep green.
The foliage is often whorled.
The profuse scarlet-red funnel-shaped flowers, up to 1.5 inches in length, are borne in loose trusses of 2 to 7.
Hardy zones 10 to 11
Rhododendron loranthiflorum
A bushy, medium-size evergreen shrub, native to the islands close to New Guinea.
The leaves, are scaly and rusty-orange when young.
The fragrant, creamy-white tubular flowers, up to 1 inches in length, are borne in trusses of 4 or 5.
Hardy zones 10 to 11
Rhododendron lutescens
A upright, leggy, large evergreen shrub, that is native to southwestern China. Some records include: 10 years - 10 x 6.5 feet; largest on record - 24 x 17 feet.
The oval leaves are up to 5 x 1.5 inches in size. The very attractive foliage is reddish at first, turning to deep bronze-green. This Rhodo does develop autumn color despite being evergreen.
The abundant, light yellow ( with light green spotting ), broad funnel-shaped flowers, up to 2 inches across, are borne in trusses of 1 to 3 during very early to mid spring.
The stems are reddish and the attractive smooth to flaking bark is brown.
Hardy zones 7 to 8 preferring partial shade. Tolerant of sun or shade, heat and drought. It is among the easiest of Rhodos to grow however still prefers a site protected from wind.
Rhododendron macabeanum
A rounded to flat-topped, evergreen medium-size tree, native to northeast India. Some records include: 10 years - 13 feet; largest on record - 63 x 47 feet with a trunk diameter of 1 foot.
The broadly-oval, thick, leathery leaves, up to 18 x 9 inches, are glossy, very deep green above, woolly white to fawn-brown beneath. The leaves typically have a yellow midrib.
The new growth in spring is dense, woolly white and appears like candle-sticks.
The light yellow, bell-shaped ( with red-purple blotch ) flowers, up to 3.5 x 2 inches, are borne in dense trusses of 20 to 30 or more during early to mid spring.
Hardy zones 8 to 9 ( tolerating as low as 5 F ) in woodland conditions. Young plants prefer shade and mature plants enjoy sunlight. It is easy to grow despite its exotic appearance and may even self seed freely in the garden. Requires consistent moisture.
Rhododendron macgregoriae
A vigorous evergreen small tree that is native to New Guinea.
Some records include: 10 years - feet; largest on record - 17 x 7 feet.
It is among the most abundant of the tropical Vireya Rhododendrons.
The leaves, up to 3.5 inches, are deep green.
The yellow-orange tubular flowers, up to 1.5 inches in length, are borne in trusses of 8 to 15.
Hardy zones 10 to 11
Rhododendron macrophyllum ( Pacific Rhododendron )
A evergreen large shrub or small tree, native to the Pacific Coast of North America ( from Vancouver Island to near Penticton, British Columbia; south to northern California ). Some records include: 10 years - 5 feet; largest on record - 43 x 20 feet with a trunk diameter of 1.5 ( 3 at base ) feet.
The leathery oblong leaves, up to 10 x 3 inches, are luxuriant glossy mid-green above, whitish beneath.
The pink ( rarely white ), trumpet-shaped flowers, up to 2 x 1.5 inches, are borne in dense trusses ( up to 5 inches across ) of up to 20 or more, during mid spring.
The flowers are followed by red-brown capsules, up to 0.5 inches in length.
The bark is reddish-brown.
Hardy zones 7 to 9 tolerating as low as -5 F. This Rhododendron prefers cool humid summers of the forests of the Pacific Northwest. It does not tolerate the hot humid summers of the eastern U.S. however can be substituted with Rhodo. catawbiensis there. Pacific Rhododendron is unusually tolerant of dry summers with no irrigation in the Pacific Northwest and northern California. In these regions, it is usually better not to water during summer unless occasionally during prolonged drought.
* photos taken by The Wild Garden, www.nwplants.com
Rhododendron maddenii
A compact, upright, evergreen large shrub, native from the Himalayas to southeast China, south into Burma and Vietnam. Some records include: 10 years - 10 feet; largest on record - 30 x 8 feet. It generally grows much lower on open sites.
The oblanceolate leaves, up to 8 x 3 inches, are smooth waxy deep green above, gray to brownish & scaly beneath.
The very fragrant, very large, white ( with yellow basal blotch ) funnel-shaped flowers, up to 6 x 6 inches, are borne in trusses of 2 to 11 during late spring.
The attractive bark is papery to flaking and brown.
Hardy zones 8 to 10, some of the hardiest seed source has been known to tolerate as low as 8 F. Tolerant of sun and heat. Easy to grow from cuttings.
Rhododendron magnificum
A massive trunked, evergreen, medium-sized tree, native to southeast Tibet and northeast Burma.
Some records include: 10 years - 8 feet; largest on record - 60 x 45 feet with a trunk diameter of 6 feet.
The huge, oblong leaves, up to 19 x 9 inches, are deep matte green above, whitish to tan beneath.
The red-purple ( with deep red basal blotch ) funnel-shaped flowers, up to 3 inches in length, are borne in dense trusses of 12 to 30 over a long season during early to mid spring.
Hardy zones 8b to 10 tolerating as low as 10 F, requires protection from excessive wind. Requires consistent moisture. Young plants prefer shade and mature plants enjoy sunlight.
Rhododendron makinoi ( Makino Rhododendron )
A slow growing, dense, rounded, medium-sized evergreen shrub, native to Japan. Some records include: 10 years - 5 feet; largest on record - 8 x 8 feet.
The long narrow leaves, up to 7 x 1 inches, are whitish and woolly at first, turning to glossy deep green above, densely woolly brown beneath. The foliage is among the most attractive of all Rhododendrons. The foliage on some clones, esp 'Henry Dumper' may persist as long as 5 years.
The abundant, mid-pink to rosey-pink funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 5 to 10 during late spring.
The flowers may or may not have red spots.
Hardy zones 6 to 9 tolerating as low as -15 F. It thrives on the east coast as far north as Boston and also in the Pacific Northwest. Heat tolerant.
* photos taken on May 7 2014 @ London Town Gardens, Edgewater, MD
Rhododendron mallotum
An erect, evergreen large shrub to small tree, native from western China into northeast Burma. Some records include: 10 years - 10 feet; largest on record - 27 x 12 feet.
The very stiff, very thick, leathery, stiff, oblanceolate leaves, up to 9 x 3 inches, are deep green above, woolly cinnamon-orange beneath.
The intense scarlet-red, funnel-shaped flowers, up to 2 inches in length, are borne in very dense trusses of up to 20 during mid spring.
The young stems are hairy gray to brown.
The attractive bark is shiny bronze.
Hardy zones 7 to 9
Rhododendron maximum ( Rosebay Rhododendron )
A fast growing, evergreen small tree, native to eastern North America ( from western New York State to far northern New Hampshire to Nova Scotia; south to northern Alabama to northern Georgia to Delaware ). Some records include: fastest recorded growth rate - 2 feet; 10 years - 13 feet; 15 years - 20 feet; largest on record - 50 x 35 feet with a trunk diameter of 1.3 feet.
The obovate leaves, up to 14 x 4 inches, are smooth glossy deep green above, light green or whitish finely hairy beneath.
The white to pinkish-purple ( spotted yellowish-green ) bell-shaped flowers, up to 1.3 inches in length, are borne in trusses during early summer.
Hardy zones 3 to 8. Heat tolerant. Prefers a site protected from excessive wind.
* photo taken on August 3 2010 @ University of Guelph Arboretum, Ontario
* photos taken on June 3 2012 in Columbia, MD
* photos taken on Jan 14 2013 in Columbia, MD
* photos taken on Nov 28 2013 in Luzerne Co., PA
* photos taken on June 7 2014 in Columbia, MD
* photos taken on May 3 2018 @ Montpelior Mansion, Laurel, MD
* photos taken on Jan 26 2021 in Columbia, MD
* photos taken on June 1 2021 in Columbia, MD
* historic archive photo
* photos taken on June 1 2022 in Columbia, MD
* photo taken on June 2 2023 in Columbia, MD
* photo taken on July 3 2023 in Columbia, MD
* photos taken on May 24 2024 in Columbia, MD
'Summertime'
The flowers are white except for the petal tips which are flushed red-purple.
Rhododendron megeratum
A rare, compact, low, spreading evergreen groundcover shrub that is native from northeast India to western China and northeast Burma.
Some records include: 10 years - 1.5 feet; largest on record - 3.5 feet.
The round leaves, up to 1.5 x 0.8 inches in size, are glossy deep green above, woolly white beneath.
The white to creamy-yellow, wide bell-shaped flowers, up to 2 inches in length, are borne in trusses of up to 3 during mid spring.
The bark is purple and peeling and the stems are very hairy.
Hardy zones 8 to 9 ( tolerating as low as 5 F ) preferring protection from excessive wind.
Rhododendron mekongense ( Makong Rhodo )
A moderately fast growing, medium-size deciduous shrub, native from the Himalayas to western China and northern Burma. Some records include: 10 years - 3 feet; largest on record - 7 feet.
The aromatic, obovate leaves, up to 2.3 x 1.2 inches in size, are blue-green.
The light yellow funnel-shaped flowers, up to 1 inch in length, are borne in trusses during late spring.
Hardy zones 5 to 10
Rhododendron micranthum ( Mandshurian Rhododendron )
An upright, evergreen shrub, reaching up to 8 x 6 feet in size, that is native to mountains in western and northern China as well as Korea. Some records include: 10 years - 5 feet.
The leathery, oblanceolate or narrow-elliptical leaves, up to 2.3 x 1 ( rarely over 1.6 x 0.5 ) inches, are luxuriant mid-green. The foliage appears more like that of the genus Ledum that that of a Rhododendron.
The white flowers, up to 0.5 inches wide, are borne on clusters of up to 20 during early summer.
Hardy zones 5a to 8 ( tolerates -25 F ) in partial shade. It is more tolerant of alkaline soils than most Rhodos.
* photo of unknown internet source
Rhododendron minus ( Piedmont Rhodo )
An attractive, medium-size small shrub, native to the southeastern U.S. ( from southeast Kentucky to central North Carolina; south to northwest Florida to central Georgia ). Some records include: fastest recorded growth rate - 20 inches; 10 years - 5 x 4 feet; largest on record - 12 x 12 feet.
The pointed, elliptical leaves, up to 5 x 2 ( rarely over 3 ) inches, are glossy deep green above, red-brown densely scaly beneath.
The white to pink or purple pink funnel-shaped flowers, up to 1.5 x 1.5 inches, are borne in dense trusses of 6 to 12 and up to 3 inches across during mid spring.
Hardy zones 4 to 9 tolerating -30 F. It is a parent of the popular PJM Rhodo and is every bit as attractive if not more.
Rhododendron monstroseanum
A magnificent small evergreen tree, native to southern Tibet.
Some records include: largest on record - 50 ( rarely over 30 ) feet with a trunk diameter of 9 inches.
The huge, deeply-veined, elliptical leaves, up to 19 x 4 inches, are deep green.
The light pink, funnel-shaped flowers are borne in huge dense trusses of 15 to 20 during early spring.
Hardy zones 7b to 9
Rhododendron morrii
A spreading, small evergreen tree, native to mountains of Taiwan at elevations of 6000 to
10 000 feet.
Some records include: 10 years - 10 feet; largest on record - 33 x 8 feet.
The attractive narrow leaves, up to 6 x 2 inches, are blackish-purple hairy at first, turning to glossy deep green.
The profuse, pure white, broad bell-shaped flowers, up to 1.5 inches in length, are borne in trusses of 12 to 15 during mid spring.
Hardy zones 6a to 9. Prefers sun in cooler climates, dappled shade in hot climates.
Rhododendron moupinense ( Moupin Rhodo )
A compact, rounded to spreading small evergreen shrub, native to western China. Some records include: 10 years - 5 x 4 feet; largest on record - 6.5 x 6.5 feet.
The thick, bristly edged, oval leaves, up to 1.8 x 1 inches, are bronze-red at first, turning to very glossy deep green above, scaly light green beneath.
The pure white ( with red dots inside ), funnel-shaped flowers, up to 2 x 2 inches, are borne in pairs or singly during late winter to early spring. The flowers are sometimes flushed pink.
There is a rare form with deep pink flowers.
The young shoots are bristly and the attractive peeling bark is reddish-brown.
Hardy zones 6b to 9 thriving best in a woodland understory. It is easy to grow and often produces abundant seed. It should be protected from excessive wind or late spring frost due to its early flowering habit.
Rhododendron mucronulatum ( Korean Rhododendron )
An open medium-size deciduous shrub, native eastern Russia, Mongolia, northern and central China to Korea and Japan. Some records include: fastest recorded growth rate - 1 foot; 10 years - 10 x 6 feet ( usually no more than 8 x 5 feet ); largest on record - 15 x 12 feet.
The thin, pointed, elliptical leaves are up to 4 x 1.5 inches in size. The foliage is deep green persisting late in autumn when it puts on an excellent show of color ranging from yellow to red.
The bright purplish-pink ( with blue anthers ) broad funnel-shaped flowers, up to 2 inches in length, are borne solitarily during early spring before the foliage emerges.
The bark on the trunk is light brown.
Hardy zones 3 to 7 preferring a site protected from excessive wind such as a woodland understory.
* photos taken on March 2010 @ U.S. National Arboretum, DC
* photos taken on Mar 23 2011 @ Brookside Gardens, Wheaton, MD
* photo taken on Mar 26 2021 @ U.S. National Arboretum, Wash, D.C.
* historical archive photos
'Cornell Pink'
Vigorous, broad, upright, reaching up to 8 feet in 10 years, and eventually 15 x 8.6 feet with large, pure mid-pink flowers.
* photos taken on March 28 2010 @ U.S. National Arboretum, D.C.
* photos taken on Mar 23 2011 @ Brookside Gardens, Wheaton, MD
'Crater's Edge'
Dark pink flowers.
'Mahogany's Red'
Rich purplish-red flowers with bronze tinge.
'Winter Brightness'
Pale purple flowers.
Rhododendron neriflorum
A compact, spreading large evergreen shrub, native from southwestern China to Indonesia. Some records include: 10 years - 13 x 13 feet; largest on record - 23 x 13 feet.
The oblong leaves, up to 5 x 1.5 inches, are deep green above, blue-white beneath.
The scarlet-red, narrow bell-shaped flowers, up to 2 inches in length, are borne in trusses of 6 to 12 during mid spring.
The stems are hairy.
Hardy zones 6b to 10 preferring a site protected from excessive wind.
'Phaedropum'
Attractive foliage is gray to blue-green beneath. It blooms as usual during mid spring, however also often blooms sporadically during summer.
Hardy north to zone 7a
Rhododendron niveum ( Niveum Rhododendron )
A rounded, large evergreen shrub, native to the Himalayas at elevations of 9500 to 12 000 feet, where it is endangered. Some records include: 10 years - 5 feet; largest on record - 20 x 12 feet.
The oblong leaves, up to 10 x 2.5 inches, are whitish hairy at first, turning to smooth deep green above, woolly fawn-brown beneath.
The lilac-purple, bell-shaped flowers, up to 2 inches in length, are borne in very dense trusses of 15 to 30 during mid-spring.
The attractive flaking bark is light gray to brown.
Hardy zones 7 to 9 tolerating as low as -5 F.
'Tower Court'
Violet flowers, otherwise the same.
Rhododendron nuttallii
A straggly to upright evergreen small tree, native to temperate rainforests of the Himalayas to western China; south to northern India to northern Burma. Some records include: largest on record - 35 x 20 feet.
The huge, deeply-veined, thick, wrinkled, oblong leaves, up to 12 x 4.5 inches, are metallic-purple at first, turning to deep green.
The very large, creamy-white ( with deep yellow throat ), bell-shaped flowers, up to 6 inches in length, are borne in trusses of 3 to 7 during mid spring. The flowers have long stamens.
The attractive bark is dark purplish-brown.
Hardy zones 8b to 10 tolerating as low as 15 F. It is sun tolerant but does appreciate protection from excessive wind.
Rhododendron oligocarpum
A beautiful, vigorous evergreen large shrub to small tree, , reaching up to 23 feet, that is native to Guangxi & Guizhou Provinces in China.
The deeply veined, elliptic to oblong leaves, up to 3.2 x 1.3 inches, are hairy at first, turning to green. The leaves persist up to 3 years.
The pink funnel-shaped flowers are borne in trusses ( up to 4 inches across ) of 4 to 6 during
Hardy zones 6 to 8. Easy to grow in the Pacific Northwest. Generally not bothered by pests or disease.
Rhododendron orbiculare ( Orbicular Rhodo )
An attractive, dense, upright, compact, evergreen large shrub to small tree, typically reaching around 10 feet, that is native to Sichuan Province in western China. Some records include: 10 years - 10 x 10 feet; largest on record - 50 x 20 feet ( extreme age - rarely over 20 x 20 ).
The rounded leaves, up to 5 x 4 inches, are luxuriant mid-green above, blue-white beneath. The leaves are deeply notched at the base. The thick, leathery leaves have a prominent bright green midrib.
The mid-pink ( less often deep red ), bell-shaped flowers, up to 2.5 x 2.5 inches, are borne in loose trusses ( up to 6 inches across ) of 7 to 10 during mid-spring.
The shoots are purplish.
Hardy zones 6 to 8 in full sun to partial shade.
Rhododendron orbiculatum
A compact, medium-size, evergreen shrub, native to Borneo. This is one of the tropical Vireya Rhododendrons.
The thick, rounded leaves, up to 4 inches in length, are green.
The large, fragrant, white or silver-pink orchid-like flowers, up to 2.5 inches in length, are borne in loose trusses of 5 or less.
Hardy zones 10 to 11
Rhododendron oreodoxa
A very attractive, vigorous, open, upright, evergreen small tree, reaching a maximum size of 40 ( rarely over 23 x 10 ) feet, that is native from eastern Tibet to central China. Some records include: fastest recorded growth rate - 15 inches.
The leathery, elliptical leaves, up to 4.5 x 2 inches, are mid-green above, blue-green beneath.
The pink, bell-shaped flowers, up to 2 inches in length, are borne in trusses of 10 to 12 during early spring.
Hardy zones 6 to 9 tolerating as low as -15 F. It prefers a continental climate.
Rhododendron oreotrepes
An upright semi-evergreen to evergreen large shrub to small tree, native to sw Szechuan & nw Yunnan Provinces in China at elevations of 9000 to 13 000 feet. Some records include: 10 years - 10 x 10 feet; largest on record - 33 x 17 feet.
The aromatic, attractive, oblong leaves, up to 3.5 x 2 inches, are scaly blue-green above, bluish-white beneath.
The profuse, rose-pink to purple funnel-shaped flowers, up to 2 x 2.5 inches, are borne in loose trusses of 3 to 11 during mid spring.
The stems are glaucous-blue.
Hardy zones 6 to 8, thriving as far north as Philly. In zone 6 and 7 if may become deciduous during the coldest of winters - do not be alarmed if the leaves fall off mid winter.
Rhododendron orthocladum
A dense, compact, mounded, dwarf evergreen shrub, native to mountains of southwestern China. Some records include: 10 years - 2 feet; largest on record - 4.5 feet.
The very small, elliptical leaves, up to 0.7 x 0.2 inches, are gray-green above, scaly yellow-brown beneath.
The small, purple to purple-blue, funnel-shaped flowers, are borne in trusses of 4 during early spring.
Hardy zones 5 to 9
Rhododendron pachysanthum
A very handsome rounded, bushy, compact, medium-size evergreen shrub, native to Taiwan. Some records include: 10 years - 5 feet; largest on record - 8 x 8 feet.
The leathery, oblong leaves, up to 4 x 2 inches, are silvery hairy at first, turning to deep green above, woolly tan-brown beneath.
The white ( densely spotted deep-red ) funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 8 to 20 during mid spring.
Hardy zones 6b to 9. Easy to grow.
Rhododendron pachytrichum
A large, evergreen shrub, reaching up to 18 feet, that is native to southwest Sichuan and northeast Yunnan Provinces in southwestern China.
The narrowly-oblong leaves are up to 5.5 x 1.8 inches in size. The foliage is mid-green above, greenish-white beneath.
The white to pale rosy-pink, bell-shaped flowers, up to 2 inches long, are borne in clusters of 7 to 10 during late spring.
Hardy zones 7 to 8 ( tolerating -5 F ).
Rhododendron pemakoense
A dwarf, compact, suckering, small, prostrate to mounding evergreen shrub, native to mountains of southwest China at elevations of 9500 to 10 000 feet. Some records include: 10 years - 16 inches x 2 feet; largest on record - 2.8 x 3.5 feet.
The leaves, up to 1.3 x 0.5 inches, are green above, golden to brown scaly beneath.
The abundant, purplish-pink, narrow bell-shaped flowers, up to 1.5 inches in length, are borne singly or paired during early spring.
Hardy zones 6 to 9 and easy to grow. Thrives in a rock garden setting but only with an overhead canopy of tall trees which help protect from late spring frost.
Rhododendron phaeochrysum
A compact, upright, evergreen large shrub, reaching a maximum size of 15 x 15 feet, that is native to mountains of southwestern China. Some records include: 10 years - 13 x 10 feet.
The leathery, oblong leaves, up to 6 x 2.3 inches, are almost white to pale gray, turning to deep blue-green above, golden woolly beneath.
The abundant, white, bell-shaped flowers, up to 2 inches in length, are borne in trusses of 15 or less, during early spring.
Hardy zones 7a to 10
Rhododendron pleianthum
A evergreen large shrub, reaching a maximum height of 20 feet, that is native to New Guinea.
This is one of the tropical Vireya Rhododendrons.
The leaves are carried in whorls of 5 to 7.
The very fragrant, pink, tubular flowers, up to 4 inches in length, are borne in trusses of 15 to 20.
Hardy zones 10 to 11.
Rhododendron polycladum
A upright, compact, small, evergreen shrub, reaching a maximum size of 5 x 5 feet, that is native to high mountains in Yunnan Province in western China.
Some records include: 10 years - 3 feet.
The narrow-elliptic leaves, up to 1 x 0.3 inches in size, are deep green above, brown scaly beneath.
The small, purplish-blue, funnel-shaped flowers, up to 0.5 inches in length, are borne in trusses of 5 to 6 during early spring, often repeating during early fall.
Hardy zones 7 to 10, thriving in coastal maritime climates.
Rhododendron ponticum ( Pontic Rhododendron )
A very fast growing, suckering, spreading, evergreen large shrub to small tree, native to the Mediterranean region of Europe and western Asia. It has also naturalized in parts of the British Isles. Some records include: 10 years - 23 feet; largest on record - 36 x 30 feet with a trunk diameter of 2 feet. One Pontic Rhododendron was reported as 23 x 142 feet in the 1800s however much of the spread may have been through self-layering. It makes an excellent hedge and windbreak but has become an invasive weed in some areas where it is not native.
The lance-shaped leaves, up to 10 x 3 inches, are glossy deep-green above, pale green beneath.
The reddish-purple, funnel-shaped flowers, up to 2 inches in length, are borne in dense trusses of 10 to 15 during early summer.
The smooth bark is brown.
Hardy zones 5 to 9 in sun or deep shade. Heat tolerant, it is very tough and may even be invasive on some sites. It often self propagated by layering when branches lay on the ground.
* photo of unknown internet source
* historical archive photo
'Variegatum'
Extremely attractive long narrow leaves that are deep glossy green with a bold silvery-white margin.
Flowers are attractive deep pink.
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
Rhododendron praestans
A dense evergreen small tree, native to southeast Tibet and Yunnan Province in China. Some records include: 10 years - 5 feet; largest on record - 33 x 8 feet.
The huge, oblong leaves, up to 24 x 10 inches, are glossy deep green above,glossy tan beneath.
The almost white to reddish-pink funnel-shaped flowers, up to inches in length, are borne in trusses of 15 to 20 during mid spring.
The bark is light brown and flaking.
Hardy zones 7 to 9
Rhododendron praevernum
A handsome, flat crowned, large evergreen shrub, that is native to central China. Some records include: 10 years - 13 feet; largest on record - 23 feet with a trunk diameter of 10 inches.
The drooping, leathery, elliptical leaves, up to 7.5 x 2 inches in size, are deep green.
The pale pink, funnel-shaped flowers are borne in trusses during early spring.
Hardy zones 7a to 9. It is more tolerant of hot humid summers than many Rhododendrons.
Rhododendron prostitum
A evergreen, small to medium size tree, native to western China and northern Burma where it is almost extinct in the wild. Some records include: 10 years - 20 feet; largest on record - 100 x 33 feet with a trunk diameter of 6 feet. Slow growing but very long lived, up to 300 years.
The huge leaves, up to 22 x 10 inches, are hairy yellowish-gray at first, turning to green.
The creamy-white ( often rose-pink flushed ) narrow bell-shaped flowers, up to 3 inches in length, are borne in large trusses of 20 to 30 during early spring.
The stems are dense woolly yellow-gray.
Hardy zones 8 to 10. It thrives especially well in Scotland.
Rhododendron pruniflorum
A medium-sized, evergreen shrub, reaching a maximum height of 4 feet, that is native to southeast Tibet; south to northeast India to northeast Burma. Some records include: 10 years - 3.3 feet.
The aromatic, leathery, oblong leaves, up to 6 x 1.5 inches, are green.
The intense-red, bell-shaped flowers, up to 0.7 inches in length, are borne in trusses of 4 to 6 during late spring.
The flower buds are hardy to -15 F.
The attractive bark is brown and flaking.
Hardy zones 6 to 9, in sun to partial shade, tolerating as low as -15 F. Mulch during winter as 20 F kills the roots.
Rhododendron pseudochrysanthum
A slow growing, dense, compact, medium-sized, evergreen, large shrub, native to Taiwan. Some records include: 10 years - 10 x 6.5 feet; largest on record - 20 x 8 feet.
The elliptic leaves, up to 3 x 2 inches, are silvery at first, turning to glossy deep green above, woolly gray-white beneath.
The profuse, pink, bell-shaped flowers, up to 2 inches in length, are borne in dense trusses of 10 to 20 during mid spring.
The young shoots are hairy and grayish.
Hardy zones 5 to 9, preferring full sun ( not reflected ) to light shade on a site protected from excessive wind.
Rhododendron racemosum ( Racemosum Rhodo )
A stiff, upright, compact, evergreen, large shrub, native to high mountains of southwestern China. Some records include: Fastest growth rate - 1 foot; 10 years - 6 x 4 feet; largest on record - 17 x 10 feet.
The aromatic, broadly-oval leaves, up to 2.3 x 1 inches, are dull green above, bluish beneath.
The white to bright pink, broad funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 6 or less over a long season during spring.
The young shoots are deep red.
Hardy zones 6 to 8 ( possibly zone 5 on a sheltered site ).
'Forrest'
Dwarf in habit, reaching a height of 2 feet with pink flowers.
'Glendoick'
Taller in habit with dark pink flowers.
'Mary Fleming'
Reaches up to 5 feet in 15 years, eventually larger.
The pale yellow flowers are flushed with salmon.
* photos taken on Mar 27 2016 in Howard Co., MD
'Rock Rose'
Erect in habit, reaching up to 6.5 feet in 10 years, eventually more. The masses of bright pink flowers are borne during mid spring. The deep red shoots bear bright green leaves.
Rhododendron radicans ( Radicans Rhododendron )
A low, semi-prostrate evergreen shrub, native to Tibet, that is similar to Rhododendron calostrotum except much smaller in all its parts ( even more so than the similar Rhodo. keleticum ).
Some records include: 10 years - 8 x 12 inches; largest on record - 8 inches x 3 feet.
The leaves, up to 1 inch in length, are mid-green above, rusty-brown beneath.
The bright purple, funnel-shaped flowers, up to 0.7 inches in length, are borne singly during mid-spring.
Hardy zones 6 to 8.
Rhododendron recurvoides ( Recurved Rhododendron )
Slow growing, compact and dome-shaped, evergreen shrub, reaching a maximum size of 5 x 7 feet, that is native to northern Burma. Some records include: 10 years - 2 x 3 feet.
The oblanceolate leaves, up to 3 inches in length, are very deep green above, rusty-brown beneath. The foliage is very attractive.
The white ( with red spotting ), bell-shaped flowers are borne on clusters of 4 to 7 during late spring.
Hardy zones 6 to 8 in partial shade.
Rhododendron rex ( Rex Rhododendron )
A very handsome evergreen small tree, native to high mountains of southwestern China and northeast Burma. Some records include: 10 years - 6 feet; largest on record - 50 x 40 feet with a trunk diameter of 16 inches.
The oblong leaves, up to 18 x 6 inches, are densely-hairy, whitish to fawn-brown at first; turning to glossy deep green, fawn-brown beneath.
The large, light pink, funnel-shaped flowers, up to 3 inches in length, are borne in massive trusses of 20 to 30 during mid spring.
Hardy zones 7 to 9, tolerating as low as 5 F but preferring protection from excessive wind.
Rhododendron roxianum ( Roxy Rhododendron )
A very attractive, upright, large evergreen shrub, native from Tibet to Yunnan Province in western China. It often appears like a very small bonsai-like tree. Some records include: 10 years - 6.5 feet; largest on record - 15 feet.
The long narrow, thick, leathery leaves are up to 5 x 1.5 inches in size. The foliage is whitish downy at first, turning to deep green above, rusty-brown beneath.
The white, funnel-shaped flowers, up to 1 inches in length, are borne in trusses of 10 to 15 during mid-spring.
Hardy zones 6b to 9, tolerating as low as -10 F.
Rhododendron rubiginosum
A vigorous, stiff, erect, evergreen small tree, native to high mountains in Tibet, Sichuan Province in China and northeast Burma. Some records include: 10 years - 20 x 10 feet ( typically half that ); largest on record - 50 x 20 feet with a trunk diameter of 1 foot. It makes a good hedge/screen.
The elliptic leaves, up to 5 x 1.7 inches, are dull deep green above, rusty-brown beneath.
The abundant, pink to rosy-pink ( with brown spotting ), bell-shaped flowers, up to 1.5 inches in length, are borne in small trusses of 4 to 8 during mid-spring.
Hardy zones 5 to 9 and is easy to grow in sun to partial shade. Tough and easy to grow, it is tolerant of alkaline soil and wind.
Rhododendron rubropilosum
A evergreen large shrub, reaching a maximum height of 10 feet, that is native to mountains of central Taiwan.
The oblanceolate leaves, up to 2 x 0.7 inches, are green.
The pink, funnel-shaped flowers are borne in trusses during mid-summer
Hardy zones 8 to 10 tolerating as low as 5 F.
Rhododendron russatum
Typically it is a dense, bushy, low growing, prostrate, evergreen groundcover shrub, that is native from western China into northeast Burma. Some records include: 10 years - 4 x 4 feet; largest on record - 8 x 5 feet ( rarely over 1.5 x 3 feet ).
The oblong leaves, up to 3.2 x 1 inches, are deep green above; densely scaly, rusty-yellowish beneath.
The intense, dark blue-purple ( with a white throat ), funnel-shaped flowers, up to 0.7 inches in length, are borne in trusses of 5 to 10 during early spring.
Hardy zones 5 to 9 ( possibly hardy in zone 4 with snow cover ).
'Black Violet'
The darkest violet-blue flowers found on any Rhododendron; it is otherwise similar to the species.
'Collingwood Ingram'
Taller growing with rich purple flowers.
'Maryborough'
larger bluish-purple flowers.
'Night Editor'
An interesting form with twisted foliage and purple blooms.
Rhododendron x russellianum
The hybrid between Rhodo. arboreum & R. catawbiense; is a vigorous, evergreen small tree that can reach a maximum size of 50 x 15 feet with a trunk diameter of 2 feet.
The flowers are pink. Rare in North America but should be more widely planted.
Hardy north to zone 6a
Rhododendron saluenense
A vigorous, low, prostrate evergreen shrub, native to high mountains from southwestern China into northeast Burma. Some records include: 10 years - 3.3 x 3.3 feet; largest on record - 5 x 5 feet.
The aromatic, small, rounded leaves, up to 1.5 x 0.6 inches in size, are glossy green, turning purple during winter.
The abundant, dark pinkish-purple ( spotted darker ) funnel-shaped flowers, up to 1 inches in length, are borne in small trusses ( up to 1.7 inches across ) of 2 to 5 during mid spring. It often repeat blooms during autumn.
Hardy zones 5 to 9 and is very hardy and easy to grow.
Rhododendron scabrifolium
An upright, medium-sized, evergreen shrub, native to southwestern China. Some records include: 10 years - 6.5 feet; largest on record - 10 x 6 feet.
The narrow oblong leaves, up to 4 x 1 inches, are hairy mid-green.
The white to pink or deep rose-pink, funnel-shaped flowers, up to 0.7 inches in length, are borne in trusses of 2 or 3 during early spring.
Hardy zones 6b to 9, on a site with good shelter from wind.
'Spiciferum'
Profusely blooming with pink flowers with prominent stamens.
Rhododendron scintillans
Also called Rhododendron polycladum. A twiggy, small evergreen shrub, native to high mountains in Yunnan Province in southwestern China.
Some records include: 10 years - 2 x 2 feet; largest on record - 4 x 4 feet.
The elliptical leaves, up to 0.7 x 0.3 inches in size, are deep green above, yellowish scaly beneath.
The purplish-blue, funnel-shaped flowers, up to 0.5 inches in length, are borne in small trusses during mid spring.
Hardy zones 8 to 9
Rhododendron scopulorum
A compact, bushy, broadly upright, medium-sized, evergreen shrub, native to southeast Tibet. Some records include: 10 years - 6.5 feet; largest on record - 15 x 8 feet.
The leathery, oblong leaves, up to 3 x 1.5 inches in size, are glossy deep green above, scaly light green beneath.
The fragrant, white to pink, broad funnel-shaped flowers, up to 2.5 inches in length, are borne in trusses of 2 to 7 during mid to late spring.
Hardy zones 8b to 10
Rhododendron sinofalconeri ( Sinofalcon Rhodo )
A handsome, evergreen, rounded small tree, native to to cool, misty mountains of southwest Yunnan Province in China and neighboring parts of Vietnam. Some records include: 10 years - 13 feet; 70 years - 30 feet; largest on record - 66 feet. It is generally larger and more tree-like than the similar Rhodo. falconeri. and can live up to 300 years.
The thick, leathery, wrinkled, elliptical to oblong leaves are up to 13 x 6.5 inches in size. The foliage is blue-green above, woolly brown beneath.
The rich yellow, bell-shaped flowers are borne in large trusses of 15 to 20 during mid-spring.
The attractive bark is light brown and smooth to flaking.
Hardy zones 7 to 8 and thrives in the coastal rainforest belt from southwest British Columbia to the California Redwood forests of northern California ( may need summer watering ). It is easy to grow on moist, humus rich, well drained soil in partial to full shade with protection from excessive wind ( typical forest understory conditions ). Being native to high elevations, it likely would not thrive in the hot humid summers of the eastern U.S.
Rhododendron sinogrande ( Sinogrande Rhodo )
A fast growing, evergreen medium size tree, native from southwestern China into northern Burma, at elevations between 7000 and 13 000 feet where it sometimes forms pure stands. Some records include: 10 years - 5 feet ( average, may be more than double that ); largest on record - 50 x 33 feet with a trunk diameter of 1.5 feet. Slow growing but is very long lived, up to 300 years. It can be grown in a large pot or planter and kept well watered and fed to enjoy the humongous tropical appearing foliage.
The huge wrinkled, thick leathery leaves, up to 40 x 16 inches, are glossy deep green above, downy silvery-white beneath. The very beautiful new growth spears are silvery-gray.
The creamy-white to yellow ( blotched deep-red ) bell-shaped flowers, up to 2.5 x 3 inches, are borne in huge trusses ( up to 10 inches across ) of 20 to 30 during mid-spring.
The silvery, very stout stems are up to an inch thick and the attractive bark is rough.
Hardy zones 8 to 9 tolerating as low as 10 F. Prefers a site protected from excessive wind. They grow best in Ireland or the warmest parts of Vancouver Island and absolutely hate hot weather. Trees tend to be more tender when under the age of 6.
Requires consistent moisture. Young plants prefer shade and mature plants enjoy sunlight.
Rhododendron smirnowii ( Turkish Rhododendron )
A vigorous, upright, dense, large, evergreen shrub, native from northeast Turkey into Georgia, where it often grows at high elevations at treeline. Some records include: fastest recorded growth rate - 1 feet; 10 years - 10 x 5 feet ( often closer to 3 x 4 feet ); 20 years - 15 x 11 feet; largest on record - 20 x 15 feet.
The thick, leathery, oblong leaves are up to 7 x 2 inches in size. The foliage is densely white hairy at first, turning to smooth glossy deep green above, woolly white beneath.
The deep pink ( spotted yellow ) funnel-shaped flowers, up to 2 x 3 inches, are borne in rounded trusses of 10 to 12 during early summer.
Hardy zones 4 to 8 tolerating as low as -30 F and is very easy to grow in partial shade but is also very sun tolerant.
Rhododendron souliei
A very beautiful slow growing, open, pyramidal, evergreen large shrub, native to mountains of southwestern China. Some records include: 10 years - 10 x 6.5 feet; largest on record - 20 x 15 feet.
The leathery, rounded leaves, up to 3.5 x 2 inches, are glossy metallic blue-green above, blue-green beneath.
The pale pink to rosy-pink, funnel-shaped flowers are borne in loose trusses of 5 to 8 during late spring.
Hardy zones 6 to 8 preferring light shade. More drought tolerant than most Rhodos.
* historic archive photo
Rhododendron strigillosum
A bushy, rounded, evergreen small tree, native to southwestern China.
Some records include: 10 years - 20 x 13 feet; largest on record - 23 x 20 feet.
The drooping, leathery, oblanceolate leaves, up to 7 x 2 inches, are densely bristly at first, turning to bright-green above, hairy beneath.
The striking, scarlet-red, narrow bell-shaped flowers, up to 3 inches in length, are borne in trusses of 8 to 12 during early spring.
The leafstalks and shoots are bristly red.
Hardy zones 6 to 9 requiring woodland shelter.
Rhododendron sutchuenense ( Sichuan Rhodo )
A dome-shaped, large evergreen shrub to small tree, native to central China. Some records include: 10 years - 20 x 17 feet; largest on record - 36 x 25 feet with a trunk diameter of 9 inches.
The leathery, oblanceolate leaves, up to 12 x 3.5 inches, are smooth deep green above, pale green beneath. The foliage droops and curls during cold weather.
The long persisting, light pink ( spotted deep red ), broad bell-shaped flowers, are borne in large open trusses of 12 or less during early spring.
The shoots are stout.
Hardy zones 6 to 8 tolerating as low as -15 F. Preferring partial shade and a site protected from excessive wind ( typical woodland understory conditions ).
Rhododendron taliense
A compact, medium size evergreen shrub, native to Yunnan Province of China.
Some records include: 10 years - 13 feet; largest on record - 13 feet.
The leaves, up to 5 x 1.5 inches, are deep green above, tawny-brown woolly beneath.
The creamy-white, funnel-shaped flowers, up to inches in length, are borne in trusses during mid spring.
Hardy zones 6 to 9 tolerating as low as -10 F
Rhododendron tephropeplum
A compact, evergreen small shrub, that is native to high mountain meadows in the Himalayas ( from northeast India to southeast Tibet and northeast Yunnan; south to northeast Burma ). Some records include: 10 years - 4 x 3.3 feet; largest on record - 5 feet.
The narrow-elliptical leaves, up to 5 x 1.6 ( rarely over 3 ) inches in size, are very deep green above, bluish beneath.
The pink to red-purple, narrow bell-shaped flowers, up to inches in length, are borne in trusses of 3 to 9 during mid spring.
Hardy zones 7 to 9 requiring protection from excessive wind.
Rhododendron thomsonii ( Thompson Rhododendron )
A bushy, rounded, evergreen, small tree, native to the Himalayas ( from northeast India to southern Tibet and Bhutan ). Some records include: 10 years - 13 feet ( typically closer to 5 feet ); largest on record - 40 x 20 feet with a trunk diameter of 9 inches ( typically about half that ).
The thick, leathery, oval leaves, up to 5 x 2.5 inches, are deep green above, blue-gray beneath. The leaves generally persist no more than 2 years.
The intense red ( spotted darker ), bell-shaped flowers, up to 2.5 x 2.3 inches, are borne in loose trusses of 6 to 13 during early to mid spring.
The attractive bark is reddish-brown peeling to reveal a fresh pinkish layer beneath.
Hardy zones 6 to 8 preferring woodland shelter. It typically profusely sets seed, so deadheading is recommended in redirect energy into increased foliage and growth.
Rhododendron trichostomum
A dense, compact, small, evergreen shrub, native to high mountains of western China. Some records include: 10 years - 4 x 3.3 feet; largest on record - 5 x 3.5 feet. An excellent choice for the rock garden.
The stiff, leathery, narrow leaves, up to 1.3 x 0.3 inches in size, are deep green above, brown felted beneath.
The long lasting, very small, white to pink or reddish-pink funnel-shaped flowers, up to 0.7 inches in length, are borne in dense rounded trusses of 10 to 20 during late spring.
The young stems are bristly.
Hardy zones 6b to 9 ( seed source from southern Qinghai Province likely hardy to at least zone 5 ) preferring full sun.
Rhododendron tsangpoense
A small evergreen shrub, that is native to mountains of southern Tibet. Some records include: 10 years - 32 x 40 inches; largest on record - 10 feet.
The aromatic leaves, up to 1 inch in length, are deep green above, very scaly gray-blue beneath.
The abundant, pink to pink-purple, broad bell-shaped flowers are borne during mid spring, often repeating during autumn.
Hardy zones 7 to 9.
Rhododendron tuba
A very beautiful evergreen large shrub, , reaching a maximum height of 15 feet, that is native to eastern New Guinea.
This is one of the tropical Vireya Rhododendrons.
The rounded leaves are glossy blue-green.
The sweetly fragrant, pure white to pale pink tubular curved flowers, up to 3 inches in length, are borne in trusses of 5 to 7.
Hardy zones 9 to 11
Rhododendron valentinianum
An attractive slow growing, very dense, small evergreen shrub, native from southwestern China into northeast Burma and northern Vietnam. Some records include: 10 years - 3.3 feet; largest on record - 10 feet.
The thick, leathery, oblong leaves, up to 4 x 2.5 ( rarely over 2 x 1 ) inches in size, are very deep green above, brown scaly beneath.
The mid-yellow, narrow bell-shaped flowers, up to 1.5 inches in length, are borne in trusses of 2 to 6 during early spring.
Hardy zones 7b to 10 preferring a site protected from wind. Thrives especially well in the San Francisco area.
Rhododendron veitchianum
A very showy, spreading, medium sized, evergreen shrub, native to Burma, Laos, Thailand & Vietnam. Some records include: 10 years - 5 feet; largest on record - 12+ x 8 feet.
The obovate leaves, up to 4 x 1.7 inches, are glossy deep green.
The large, very fragrant, pure white ( with a deep yellow blotch ) funnel-shaped flowers, up to 3 x 5 inches, are borne in trusses of 5 or less during spring.
The very attractive peeling bark is reddish-brown.
Hardy zones 8b to 10
Rhododendron vernicosum
A evergreen small tree native to southwest China at elevations of 9000 to 14 000 feet. Some records include: 10 years - 4 x 4 feet; largest on record - 27 feet with a trunk diameter of 10 inches. Long lived as long as its need of well drained soil is met.
The leathery, oblong-oval leaves, up to 5 x 1.8 inches in size, are deep green above, blue-green beneath.
The light pink, funnel-shaped flowers, up to 2 inches in length, are borne in trusses of 6 to 12 during mid spring.
Hardy zones 6a to 9, tolerating as low as -15 F. Thrives especially well in Scotland.
Rhododendron wardii ( Ward's Rhododendron )
A beautiful, broadly upright, evergreen large shrub or small tree, native to mountains of southwestern China. Some records include: 10 years - 8 feet; largest on record - 33 x 15 ( rarely over 20 ) feet.
The leathery, broadly-oval leaves are up to 4 x 2.5 or rarely 7 x 2.5 inches in size. The foliage is blue-green turning to luxuriant deep green above, blue-white beneath.
The abundant, bright yellow, saucer-shaped flowers, up to 3 inches across, are borne in loose trusses of 5 to 14 during late spring. The flowers are often blotched deep-red.
The rough, flaking bark is gray-brown to grayish-white. The young stems and leaf stalks are deep red.
Hardy zones 6 to 8, preferring a site protected from excessive wind.
'Finesse'
Compact and dense, with pure bright yellow flowers.
* photo taken by Milan Havlis, owner of central Europe's premier plant nursery
Rhododendron williamsianum
A very slow growing, dense, rounded, evergreen large shrub, native to mountains of southwestern China. Some records include: 10 years - 5 x 5 feet; largest on record - 25 x 10 feet ( rarely more than 8 feet in height ).
The leathery, broad-ovate leaves, up to 3 x 1.5 inches, are bronzed and bristly at first, turning to deep green above, bluish beneath.
The light pink ( with darker spotting ), dainty, bell-shaped flowers, up to 2 inches across, are borne in loose trusses of 2 or 3 during mid spring.
The young shoots are bronze in color.
Hardy zones 6 to 8 preferring protection from excessive wind. Sun tolerant ( prefers light shade ) but requires both a wet climate and very well drained soil preferrably in a raised bed or on a slope.
* historic archive photo
'Exbury White'
Flowers are white.
Rhododendron williamsii
A vigorous, bushy, medium-size evergreen shrub, reaching a maximum height of 10 feet, that is native to the Phillipines.
This is one of the tropical Vireya Rhododendrons.
The leaves, up to inches, are
The white, funnel-shaped flowers, up to 1.5 inches in length, are borne in trusses of 5 to 8.
Hardy zones 10 to 11
Rhododendron yakushimanum ( Yaku Rhododendron )
Considered by some to be a regional variant of Rhodo. degronianum. A slow growing, compact, dome shaped, small to medium-size evergreen shrub, native to Yakushima island in Japan. It rarely reached as much as 10 x 8 feet in cultivation. Some records include: 10 years - 5 x 5 feet; largest on record - 12 x 22 feet ( reported as high as 25 feet in the wild ).
The deeply-veined, broadly-oval leaves, up to 5.3 x 1.2 inches in size, are glossy deep green above, thick woolly fawn-brown beneath. The attractive foliage is often silvery at first and may persist as long as 7 years.
The long lasting, light pink ( often fading to white ), bell-shaped flowers, up to 2 inches across, are borne in dense trusses of 8 to 14 during late spring. The flowers are reddish-pink in bud.
The stems are white felted.
Hardy zones 4 to 8. it is easily propagated from cuttings. Easy to grow, it is very wind tolerant which is unusual for Rhododendrons.
* photos taken on June 7 2012 in Columbia, MD
* photos taken on May 6 2015 in Columbia, MD
* photo taken on May 15 2015 in Columbia, MD
* photos taken on June 24 2015 in Columbia, MD
'Bashful'
A compact, spreading, small evergreen shrub. Some records include: 10 years - 3.3 feet; largest on record - 4 x 4 feet.
The narrow leaves are silvery at first, turning to dull deep green.
The pink ( with red-brown blotch ) funnel-shaped flowers, up to inches in length, are borne during mid spring.
Hardy zones 5 to 9
'Crete'
An attractive, compact, domed shrub reaching up to 6 x 6 ( rarely over 3 ) feet in 10 years, eventually reaching up to 7 feet.
The handsome, narrow foliage is glossy deep green above, fuzzy beneath.
The flowers, up to 1.6 inches, are light purple fading to white, borne in very tight domed trusses up to 4 inches across.
Hardy zones 4 to 8
* photos taken on May 27 2017 @ Meadowlark Botanical Gardens, Vienna, VA
* photo taken on Apr 27 2020 in Howard Co., MD
* photo taken on Apr 17 2021 in Columbia, MD
'Doc'
An attractive, vigorous, compact, upright, small evergreen shrub
Some records include: 10 years - 3 x 3 feet; largest on record - 5 x 5 feet.
The rose-pink, funnel-shaped flowers, up to 2 inches in width, are borne in dense rounded trusses of 9 during mid-spring.
Hardy zones 5 to 9
'Dopey'
A vigorous, upright, compact, small evergreen shrub. Some records include: 10 years - 3 x 4 feet; largest on record - 5 x 4 feet.
The leaves, up to 4 inches in length, are dull green.
The long lasting, shiny red, bell-shaped flowers are borne in trusses of 16 during mid-spring.
Hardy zones 5 to 9
'Fantastica'
Vigorous but compact in habit, reaching up to 3 x 4 feet in 10 years, eventually 5 x 6.5 feet.
The elliptical leaves, up to 6 inches in length, are deep green above, tan colored and woolly beneath.
The deep pink flowers, up to 2.3 inches across, are borne on compact trusses of 18 to 20. The large flower trusses are up to 5 inches across.
Hardy zones 5 to 9, tolerating as low as -15 F.
* photos taken on May 14 2011 in Columbia, MD
'Golden Torch'
A upright, compact, medium-size evergreen shrub
Some records include: 10 years - 2.5 x 4 feet; largest on record - 5 x 5 feet.
The medium-sized leaves are dull green, persisting for 3 years.
The light yellow, funnel-shaped flowers, up to 1.5 inches, are borne in dense, rounded trusses of 13 to 15 during mid to late spring. The flower trusses are up to 4.8 inches across.
Hardy zones 5 to 9.
'Grumpy'
A compact evergreen shrub.
Some records include: 10 years - 3 x 4 feet; largest on record - 5 feet.
The recurved leaves are dull deep green.
The funnel-shaped flowers are borne in trusses of 11 during mid spring.
The flowers are orange in bud, opening to creamy-white tinged with pink.
Hardy zones 4 to 8
'Hoppy'
A vigorous, compact evergreen shrub
Some records include: 10 years - 4 feet; largest on record - 6.6 feet.
The leaves are dull deep green.
The white ( speckled green ) funnel-shaped flowers are borne in large rounded trusses of 18 during mid spring.
Hardy zones 4 to 8
'Hot Dawn'
Forms an upright evergreen shrub reaching up to 5 x 4 feet in 10 years.
The foliage is luxuriant deep green. The flowers are bright pink-red.
Hardy zones 4b to 8, tolerating as low as -25 F
'Hydon Dawn'
A vigorous, compact evergreen shrub
Some records include: 10 years - 20 inches; largest on record - 5 x 5 feet.
The leaves, up to inches, are glossy deep green above, hairy creamy-white beneath.
The frilled pink ( spotted red-brown ) funnel-shaped flowers are borne in dense, large, rounded trusses of 14 to 18 during mid spring.
Hardy zones 5 to 9, tolerant of full sun and wind.
'Ken Janeck'
A slow growing, compact, dense, spreading, mounded shrub, reaching up to 3 x 4 feet in 10 years, though larger after many decades. The largest on record is 8 x 14 feet.
The foliage is glossy deep green above, white fuzzy beneath.
The large flowers, up to 2.4 inches across, are borne on domed trusses up to 6 inches across.
The flowers are pale pink fading to white. The flower buds are deep pink.
The large flower buds are silvery-white.
Hardy zones 4 to 8 tolerating as low as -25 F. Wind tolerant.
* photo taken on May 7 2023 in Columbia, MD
'Mist Maiden'
Vigorous growing to 3 x 5 feet in 10 years and eventually to 5 x 5 feet. The foliage is glossy deep green and the flowers are pink fading to white. The flowers, up to 2.5 inches across, are deep pink in bud. The stems and buds are silvery-gray.
Hardy north to zone 4, tolerating as low as -25 F.
* photos taken on May 7 2014 @ London Town Gardens, Edgewater, MD
'Percy Wiseman'
A compact, vigorous growing plant reaching up to 3 x 5 feet in 10 years, with a maximum eventual size of 7 x 7 feet.
The attractive, glossy, very deep green leaves are up to 4 x 1 inch in size. The very profuse, mid-season, funnel-shaped flowers are pink ( later fading to white ) with orange spots and a pale yellow center. The flowers, up to 2.5 inches across, are borne in trusses of up to 14 during late spring.
Hardy zone 5 to 8
* photos taken on May 4 2012 in Baltimore, MD
'Peste's Blue Ice'
A dense, compact, evergreen shrub, reaching a maximum size of 6 x 8 feet.
The deep purple-pink fading to very light purple ( lightly spotted green ) funnel-shaped flowers are borne in trusses of 21 during mid spring.
Hardy zones 5 to 9
'Phetteplace'
The giant of the family, in fact one is known to have reached 12 x 12 feet in 40 years at Gossler Farms Nursery in Oregon.
The foliage is larger than average for a Yakushima Rhododendron.
The very showy, large flowers are pale pink.
Hardy zones 5 to 8 in partial shade.
'Renoir'
A compact and upright shrub reaching up to 4 feet in 10 years, with a maximum eventual size of 5 x 4.5 feet.
The foliage is deep green.
It has abundant mid season rose-pink bell shaped flowers ) that have crimson spots and a white throat ) are borne late spring. The large flowers, up to 3.2 inches across, are borne on trusses up to 6.5 inches across.
The flowers are borne in rounded trusses of 11, during late spring.
Hardy zones 5 to 8
'Surrey Heath'
A very dense, compact evergreen shrub. Some records include: 10 years - 3 feet;
largest on record - 5 feet. The foliage is bright green.
The rose-pink ( lighter in the center ) funnel-shaped flowers are borne in trusses of during mid spring.
Hardy zones 5 to 9. Wind tolerant.
'Teddy Bear'
The hybrid of R. bureavii & R. yakushimanum. Dense and spreading, reaching up to 4 x 4 feet in 10 years.
The very attractive leaves, up to 5 inches in length, are glossy deep green above, orange woolly beneath.
The large, pink flowers, up to 2.5 inches across, are borne in clusters of 8 to 10.
Hardy zones 6 to 9, tolerating as low as -15 F
'Titian Beauty'
A erect compact evergreen shrub reaching up to 5 x 5 feet in 10 years and a maximum eventual size of 7 x 7 feet.
The small leaves are green.
The deep red, funnel-shaped flowers, up to 2.5 inches across, are borne during mid spring.
Hardy zones 5 to 9
'Yaku Prince'
Dense and low growing, only reaching up to 3 x 4 feet in 10 years with an eventual size up to 8 x 6.8 feet. The long leaves, up to 4 inches in length, are deep green above, tan-orange felted beneath.
The flowers, up to 2.5 inches across, are pale pink ( deep pink in bud ).
Hardy zones 4b to 8
* photos taken on May 3 2015 in Ellicott City, MD
* photo taken on Oct 3 2015 in Columbia, MD
* photos taken on Apr 29 2016 in Columbia, MD
* photos taken on May 9 2016 in Columbia, MD
* photo taken on Jun 20 2016 in Columbia, MD
* photo taken on May 17 2017 in Columbia, MD
* photos taken on May 11 2020 in Columbia, MD
* photo taken on Apr 30 2022 in Columbia, MD
* photos taken on Oct 9 2022 in Columbia, MD
* photo taken on June 1 2023 in Columbia, MD
* photo taken on July 2 2023 in Columbia, MD
* photo taken on Aug 25 2023 in Columbia, MD
* photo taken on May 6 2023 in Columbia, MD
'Yaku Princess'
Dense and low growing, only reaching up to 3 x 4 feet in 10 years with an eventual size up to 8 x 6.8 feet. The long leaves, up to 4 inches in length, are deep green above, tan-orange felted beneath.
The flowers, up to 2.5 inches across, are pale pink fading to white ( deep pink in bud ).
Hardy zones 4b to 8
* photo taken on May 5 2010 in Columbia, MD
* photo taken on Aug 20 2011 @ Brookside Gardens, Wheaton, MD
* photos taken on May 3 2012 in Columbia, MD
Rhododendron yunnanense
A attractive, fast growing, upright, semi-evergreen large shrub, native from western China into northeast Burma. Some records include: 10 years - 10 feet; largest on record - 23 x 13 feet.
The narrow elliptical leaves, up to 4 x 1.5 inches, are gray-green to deep green.
The profuse, large, white, pink to purple-pink ( with red throat ), funnel-shaped flowers, up to 2 inches across, are borne in small trusses of 3 to 5 during mid to late spring. The flowers are often spotted deep-red.
The young stems and leaf stalks are deep red.
Hardy zones 7 to 8 preferring partial shade but tolerating full sun. Does not enjoy hot summers, it grows especially well in the Pacific Northwest. In colder parts of its range, it may drops its foliage during the cold winters.
Rhododendron zaleucum
A vigorous, upright, small tree reaching 6 feet in 10 years and an eventual maximum height of 30 feet. It is native to mountains forests in Yunnan Province in southwest China as well as neighboring parts of Burma.
The narrowly-elliptic leaves are among the largest of all Rhodos reaching up to 36 inches in length. They are deep green above, bluish-white beneath.
The flowers are variable in color but are 1.5 inches in length and borne in trusses of 3 to 5.
Hardy zone 8 ( tolerating as low as 5 F ) where summers aren't too excessively hot.
Rhododendron zoelleri
A open, medium-sized, evergreen shrub, native to the Moluccas Islands and New Guinea. Some records include: 10 years - feet; largest on record - 20 feet.
This is one of the tropical Vireya Rhododendrons.
The leaves, up to 5 inches, are borne in whorls of 5.
The brilliant, almost flourescent yellow to pinkish-orange, large funnel-shaped flowers, up to 3 inches in length, are borne in open trusses of up to 8.
Hardy zones 10 to 11.
MORE RHODODENDRONS
* Additional photos of Rhododendron maximum taken on Nov 27 2015 @ Hickory Run State Park, PA
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