Monday, April 5, 2010

Hemlock - Tsuga

The Hemlocks are shade tolerant conifers making up the understory in many forests where they are native. They grow in shade or sun but do grow fastest in humus rich, PH 4 - 7, moist well drained soil. At least some shelter from wind is preferred. They hate root competition from turn and thus grow poorly in lawns. Can be propagated from rooting half hardened cuttings in late summer or sowing seeds in containers during autumn and keeping them protected from winter freezing. Western and Canadian Hemlock tolerate shearing though it is kinda pointless since it destroys the attractive natural shape. If you want something small it is better to plant something that stays small, you'll save lots of time. That being said I seen many unkempt Hemlock hedges in the Poconos in Pennsylvania sprouting 3 feet on new growth trying to revert to their natural tree form.
Tea can be made from the foliage of the Hemlock and it is very rich in Vitamin C. An excellent winter health tonic.



* photos taken on May 4 2011 in Bel Air, MD





Tsuga canadensis ( Canadian Hemlock )
Native to eastern North America ( from northern Minnesota to Batchewana, Ontario to southern Quebec to Gaspe and Cape Breton, Nova Scotia; south to Indiana to northern Georgia to Virginia ); this is a broadly conical evergreen tree which can be single or multi stemmed depending on how pruned or whether in open or shade. Training to single trunk is usually preferrable. In cooler climates the Hemlock can live very old and also grow very large. Trees almost 200 feet tall; 70 feet wide with trunk diameters up to 7 feet across were found in the original old growth forest that greeted the European settlers centuries ago. These trees were up to 1000 years old! Some very large trees still exist today with 140 foot recorded in Longwood Gardens outside Philly. It is moderately fast growing and can reach up to 50 feet tall and 20 feet wide in 20 years. 80 feet is normal for maturity. The record size for a 10 year tree is 30 x 13 feet. The fastest growth rate recorded is 4 feet with diameter increase of 0.5 inches. Though most old growth Hemlock is long gone some extremely large trees still grow in New hamburg, Ontario as well as at the Royal Botanical Gardens in Hamilton, north central Pennsylvania, and the mountain ridges of VA to the Smokey Mountains in Tennessee. Canadian Hemlock has declined considerably in Ontario, Canada as most of the old growth Hemlock stands have been cut before 1900. It is endangered in Minnesota. In the Windsor/Essex County, Ontario region; it occurred sporadically north of Leamington as well as being locally abundant the Ohio shore during the 1800s.
The linear leaves, up to 0.6 inches long, are arranged in 2 rows. The foliage is deep green above, silvery below. The leaves last up to 4 years.
The small female cones, up to 0.8 inches long, are brown and appear at the end of the branches.
The bark is red-brown with scaly ridges.
The Canadian Hemlock grows well from zone 2 to 6 and also in zones 7 in areas summers aren't excessively hot.
The Canadian Hemlock tolerates flooding, hail and ice; unfortunately it is far more prone to Woolly Agelid infestation than any other Hemlock. If the Eastern Hemlock wasn't already better adapted for cooler regions; the fact that most woolly adelgid larvae die at 0 F or colder only furthers the cause. A newly released Black Lady Bug promises to kill the Woolly Adelgid however this pest has already killed large stands of Hemlock in the southern Appalations.
Hemlocks are rarely colonizers and usually found only in old growth forests in the wild; that is because they cannot take full sun until they reach 36 inches in height. They do not enjoy being transplanted so care should be taken. Try to grow trees from local seed source as trees grown from zone 3 Quebec Canada seed may not enjoy zone 7 Maryland summers.

* photo taken by E.S. Shipp @ USDA-NRCS PLANTS Database

* photo taken by W.D. Brush @ USDA-NRCS PLANTS Database

* photo taken @ Longwood Gardens near Philly, PA

* photo taken near Wilkes-Barre, PA




* photo taken on April 5 2010 near Wilkes-Barre, PA





* photos taken on March 2010 @ U.S. National Arboretum, DC







* photos taken on July 31 2011 in Hyde Park, NY






* photo of unknown internet source

* photos taken on Nov 25 2012 near Wilkes-Barre, PA


* photos taken on Apr 21 2014 in Luzerne Co., PA





* photos taken on July 27 2015 in Bayfield, ON










* photos taken on July 27 2015 in Bayfield, Ontario


* photos taken on Apr 17 2016 @ U.S. National Arboretum, DC

* photo taken on July 16 2016 in Bayfield, ON

* photo taken on Sep 21 2016 in Columbia, MD

* photo of unknown internet source

* historical archive photos












'Albospica'
A large tree, with new growth that is white, later turning to deep green.
Some records include: 10 years - 10 x 6 feet; 35 years - 25 x 15 feet.

* photo taken on July 17 2010 @ Morris Arboretum, Philly, PA



'Aurea'
Slow growing with gold foliage that turns green as it matures. It can reach 26 feet tall and 12 feet wide.

'Beaujean'
A slow growing, compact, broad-spreading, semi-dwarf shrub.
Some records include: fastest growth rate - 4 inches; 10 years - 4 x 4 feet.
The foliage is mid-green above, silvery beneath.


* photo taken on Feb 8 2015 @ U.S. National Arboretum, DC


'Bennett'
A very compact, low, dwarf cultivar that rarely exceeds 3 feet in height. Some records include: fastest growth rate - 6 inches; 10 years - 3 x 6 feet; largest on record - 5 x 10 feet.
The leaves, up to 0.3 inches in length, are bright green.

'Coles Prostrate'
Dwarf and spreading, it can be used as a groundcover or to trail over walls.
It makes a great plant for the rock garden. Some records include: fastest growth
rate - 6 inches; 10 years - 1 x 3 feet; largest on record - 16 inches x 8 feet.
The foliage is mid-green.

* photo taken on Feb 8 2015 @ U.S. National Arboretum, DC


'Emerald King'
rich green leaves all year.

'Gentsch White'
A very attractive, dense, compact, broadly-pyramidal to rounded dwarf.
Some records include: 10 years - 8 x 3 feet.
The foliage is tipped with white, eventually turning all green.

'Gracilis'
A very attractive, rounded to flat-topped dwarf, reaching a maximum size of 6 x 8 feet in 20 years, 15 x 10 feet in 65 years recorded at Dominion Arboretum in Ottawa, Ontario. Some records include: growth rate - 4 inches.
The foliage is glossy mid-green. The stems gracefully droop at the tip.

'Hussei'
A very compact, irregular-branched, dense, upright shrub to small tree, reaching a maximum size of only 3 x 1.5 feet in 10 years or 20 x 10 feet in 35 years. The largest on record is 30 x 25 feet with a trunk diameter of 0.9 feet.
The very congested foliage is mid-green..

'Jeddelloh'
A mounding weeping dwarf, reaching up to 2 x 3 ( rarely 5 x 6 if staked )feet in 10 years. With great age it can reach a maximum size of 6 x 15 feet if not pruned.
The foliage is mid-green.

* photo taken on Aug 1 2012 in Windsor, Ontario

* photos taken on Oct 22 2012 in Columbia, MD


* photos taken on July 9 2015 in Columbia, MD



'Macrophylla'
Rapid growing with larger leaves.

'Minima'
A slow growing, dense, spreading dwarf, reaching an eventual maximum size of 5.5 x 9 ft. It is great for the rock garden.
The short needles, up to 0.25 inches in length, are gray-green.




'New Gold'
A fast growing, upright tree, similar in growth and habit to the species.
The new foliage during spring is entirely bright yellow, later deepening to mid-green.

'Sargentii' ( Sargent Weeping Hemlock )
A spectacular landscape plant for edges of patios and other focal points the Weeping Hemlock reaches up to 4 x 8 ( 6 x 4 if staked ) feet in 10 years and an eventual maximum size of 30 x 52 feet with a trunk diameter up to 4.4 feet. Some records include: 50 years - 15 x 48 feet with a trunk diameter of 3.7 feet. It is best staked upright when very young up to 3 feet or more then allowed to weep. Very large Weeping Hemlocks grow at Bryn Mawr College as well as Tyler Arboretum and Longwood Gardens near Philadelphia, PA. In addition to its graceful form, its mid green foliage is very ornamental. It is prone to the accidently introduced Woolly Agelgid insect and may need to be treated with systemic Bayer insecticide in the spring. The Weeping Hemlock as well as its parent Canadian Hemlock grow best from zones 2 to 7 in moist, fertile, well drained soil in full sun or shade ( at least some shade more preferable in zone 7 )







* photo taken on July 17 2010 @ Morris Arboretum, Philly, PA


* photos taken on Feb 8 2015 @ U.S. National Arboretum, DC


* photo taken on Aug 11 2015 in Columbia, MD

* photo taken on Sep 13 2015 in Columbia, MD

* photo taken on May 20 2016 in Columbia, MD


'Summer Snow'
Slightly slower growing and pyramidal in habit, reaching up to 15 feet in 10 years.
The foliage is creamy-white at first during spring, later turning to deep green.

Tsuga caroliniana ( Carolina Hemlock )
Native to the Appalatian Mountains from Virginia to Georgia ( with a separate disjunct natural range in the hills of eastern Ohio ); this Hemlock grows fast up to 50 feet tall and 20 feet wide in 20 years. It is not as graceful in habit as the Canadian Hemlock but still a beautiful tree. It can grow large and reach 80 feet or more. Some records include: largest on record - 200 x 35 feet with trunk diameter of 7 feet; fastest growth rate - 4 feet. It is more heat tolerant, less Woolly Adelgid prone and has a dense, broad-conical crown. The Carolina Hemlock can live up to 307 years in age.
The glossy deep green leaves, up to 1 inch in length, are arranged in 2 rows and can last up to 5 years. The needles are not flat pressed as is the Canadian Hemlock.
The Carolina Hemlock is more closely related with the Asian Hemlocks rather than the Canadian, Mountain or Western Hemlock.
Hardy zones 3 to 8. It needs humid climates but can tolerate a wide range in soil PH from 3.5 to 7. It is also more drought, pollution and wind tolerant than most other Hemlocks. It has been grown in the Pacific Northwest where it thrives.






* damage from Woolly Agelgid infestation




* historic archive photo



'Le Bar Weeping'
A dense, spreading, weeping form. Some records include: growth rate - 8 inches; 10 years - 2 x 6 feet.
The foliage is mid-green.

'Westonigra'
Compact and fast growing, reaching up to 60 x 30 feet, with very deep green foliage.

Tsuga chinensis ( Chinese Hemlock )
It is very fast growing and pyramidal when young, graceful and looks like the Canadian Hemlock as it ages. It is native to central China and can live up to 400 years, very old trees may form a massive domed canopy. Some records include: growth rate - 2 feet ( average ); 20 years - 32 x 18 feet; largest on record - 170 x 100 x 7 feet. The tallest Chinese Hemlock in Pennsylvania ( 62 feet ) grows at Morris Arboretum in Philly.
The long ( for a Hemlock ) linear leaves are glossy deep green.
The bark is an attractive buff pink to light brown.
It is hardy zones 4 to 7 so it can be grown over a wide area of North America.
Very easy to grow, it tolerates poor soil and limestone. The Chinese Hemlock is very tolerant of hot humid summers and is resistant to Woolly Agelgid, giving it high ornamental value in eastern North America.

* photos taken on October 17 2010 @ U.S. National Arboretum, D.C.

* photo taken on Mar 7 2013 @ Brookside Gardens, Wheaton, MD

* photo taken on June 23 2013 @ U.S. National Arboretum, DC

* photo taken on Feb 8 2015 @ U.S. National Arboretum, DC

* photos taken on Apr 24 2016 @ U.S. National Arboretum, DC



* photos taken on Apr 23 2017 @ Brookside Gardens, Wheaton, MD



Tsuga diversifolia ( Japanese Hemlock )
A moderate growing, horizontally branched, rounded, medium to large tree that is native to high mountains of Japan. Some records include: fastest growth rate - 2 feet; 20 years - 26 feet; largest on record - 140 x 80 feet with a trunk diameter of 5 feet. The largest known tree in Pennsylvania grows at Haverford College near Philadelphia.
The linear leaves, up to 0.6 inches, are glossy deep green and last up to 6 years.
The bark is grayish-brown.
Hardy zones 4 to 8 ( tolerates - 37 F ) in sun or shade on moist, well drained soil. This very frost and wind hardy Hemlock is even planted in the Kremlin in Moscow but is virtually unknown in North America. It is more drought, clay and urban tolerant than the Canadian Hemlock. The Japanese Hemlock is also resistant to wooly agelgid. It makes an excellent tree for cultivation in the eastern U.S. & Canada.

* photos taken on May 27 2017 @ Meadowlark Botanical Gardens, Vienna, VA


* historic archive photos




Tsuga dumosa ( Himalayan Hemlock )
A handsome massive growing Conifer only hardy north to zone 7 and preferably in maritime climates. It grows up to 50 feet in 20 years and the largest ever recorded are up to 170 feet in height and 11 feet in trunk diameter.
The 1.5 inch linear foliage is blue-green.
The Himalayan Hemlock thrives on any moist, well drained soil with a PH from 4.3 to 7.5.

* historic archive photo


Tsuga forrestii
A large tree that is only native to subalpine areas in the Yunnan Province of China.
It has a pyramidal crown and is somewhat weeping like the Cedrus deodara - Kashmir Cedar. Some records include; largest on record - 100 x 40 feet with a trunk diameter of 3.5 feet.
The deep green linear leaves are up to an inch in length.
Prefers maritime climates and is not tolerant of severe cold or heat. Prefers acidic soil with a PH from 4.5 to 6.

Tsuga heterophylla ( Western Hemlock )
A fast growing, dense, narrowly-conical, very large tree, that is native to western North America ( from Kodiak Alaska to Anchorage, Alaska to Smithers, British Columbia to Alberta's Rocky Mountains; south to Oregon to western Montana ). The Western Hemlock can easily grow to 60 x 20 feet in 20 years and will rapidly exceed 100 feet. 150 feet or more is common and this Hemlock can live as long as 1300 years. Trees as large as 312 feet in height; 70 feet in width and 15 feet in trunk diameter have been recorded in the original old growth Pacific Rainforest. It may grow to 20 feet in height in only 5 years on the best of sites. 5 foot growth rates have been recorded with the Western Hemlock.
The glossy deep green ( whitish beneath ) non-spiny tip leaves are held on horizontal branches with pendant tips. The linear leaves are up to 0.5 inches in length and persist up to 7 years.
The cones are up to 1 inch in length.
The scaly and fissured bark is reddish-brown. Its timber is used commercially and is a pale yellow in color.
It is resistant to Woolly Agelid and interior Rocky Mountain clones should be experimented with in the East. Shade tolerant but doesn't like excessive wind. It is hardy from zone 4 to 8 ( tol - 25 F ), required moist, acidic soil and prefers cool summers and a humid climate. Tolerates very acid soils. Highly recommended for Pacific Northwest Canada & U.S. as well as western Europe where it is sometimes planted for timber plantations.

* photo of unknown internet source

* photo taken by Charles A. Wellner @ USDA-NRCS PLANTS Database

* photo taken by K.D. Swan @ USDA-NRCS PLANTS Database

USDA-NRCS PLANTS Database

* historical archive photos


















'Thorsen's Weeping'
A weeping small tree if staked ( 10 years - 6 feet ), otherwise it forms a mounding mat. The foliage is luxuriant mid-green.
Hardy zones 6 to 8 ( est ).

Tsuga longibracteata ( Bristlecone Hemlock )
Also called Nothotsuga longibracteata. This southeast Chinese native is critically endangered; it is also the best Hemlock for hot humid climates though it can only tolerate as cold as 10 F. It should be tested in the southeast U.S. It looks like Canadian Hemlock and can reach up to 100 feet tall with a trunk diameter up to 3.5 feet. Some records include: 3 years - 3 feet.
The linear foliage is 1 inch long and the bark is dark brown and vertically fissured

Tsuga mertensiana ( Mountain Hemlock )
Native to western North America ( from Kodiak, Alaska to Atlin, British Columbia to Smithers, B.C. to far eastern British Columbia; south to central California to northern Idaho to western Montana ); this Hemlock is moderate growing to 33 feet tall and 17 feet in width in 20 years. It rarely exceeds 100 feet in height though some have reached up to 200 feet in height; 50 feet in width and 8.6 feet in trunk diameter. It only grows well in climates with cool summers and is not recommended for either the eastern U.S. or Ontario, Canada. However in England this tree grows very well as does the Western Hemlock and has reached sizes of 105 feet in height and 3.6 feet in diameter in 120 years. Long-lived, it can persist up to 500 years.
The blunt tipped leaves are bluish-green and the small cones ( up to 2 inches ) are purplish maturing to dark brown. The needles persist up to 3 years.
Hardy zones 4 to 7 ( possibly 3 for interior B.C. populations ) preferring high elevations or climates with cold winters and short summers. The Mountain Hemlock grows well in much of western Europe with its cool humid summers.
The Mountain Hemlock is clay tolerant. It may be prone to Woolly Agelgid on some sites.

* photo taken by Jean Pawek @ CalPhotos

USDA-NRCS PLANTS Database


* photo taken by G.B. Sudworth @ USDA-NRCS PLANTS Database

* photo taken by Charles A. Wellner @ USDA-NRCS PLANTS Database

* photo taken by Ray M. Filloon @ USDA-NRCS PLANTS Database


* historic archive photos






















* photo taken by Richard C.P. Wilson and the Marian Koshland Bioscience and Natural Resources Library


* photo taken by Herbert A. Jensen and the Marian Koshland Bioscience and Natural Resources Library


'Blue Star'
Has intense blue foliage.

'Cascade'
Compact slow growing tree

'Elizabeth'
Flat and spreading in habit, this dwarf form reaches only 3 x 6 feet in 10 years, eventually to 6 x 10 feet.
The foliage is grayish-blue.

'Mt. Hood'
Silver-gray foliage

Tsuga sieboldii
Shaped differently than the native Canadian Hemlock it is also hardier and resistant to the Wooly Agelgid and is just an awesome landscape tree. Most people in the U.S. never heard of this Hemlock and certainly nobody sells it however they should. Though upright, horizontally branched and conical rather than pendulous and graceful; it is still a beautiful conifer and enjoys hot summers unlike most hemlocks. It grows up to 2.5 feet per year though a 20 year old tree is normally not expected to exceed 27 x 20 feet. In North America this tree has already exceeded 50 feet in Philly and very old trees in the wild are known to reach 136 x 100 x 6.5 feet. Native to Japan; it is usually found at lower elevations than Tsuga diversifolia.
The soft-tipped needles, up to 1 inch in length, are glossy deep green above and whitish below.
The bark is grayish-brown.
Hardy north to zone 4a and can tolorate as low as -38F.


* photos taken on July 17 2010 @ Morris Arboretum, Philly, PA


* photo taken on Apr 24 2016 @ U.S. National Arboretum, DC

* historic archive photos



Tsuga yunnanensis ( Yunnan Hemlock )
A huge Hemlock growing to 133 feet in height and 7 feet in trunk diameter, that is native to southwestern China.
The leaves reach 1 inch in length.
It can tolerate - 30 F with no damage.

MORE HEMLOCK

* Additional photos of Tsuga canadensis taken on Nov 27 2015 @ Hickory Run State Park, PA

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