Thursday, February 2, 2012

Ornamental Rhubarb

Rheum
All species edible or ornamental prefer a full sun and a consistently moist, fertile, humus-rich, deep ( at least 3 feet ) soil. Propagation is from seed sown during spring or dividing the tough woody root system. When separating the roots while the clump is still dormant during early spring make sure each transplanted root has at least one bud. Replant at same depth that it grew originally. Seed should be sown immediately upon ripening and they are usually quick to germinate.

Rheum 'Ace of Hearts'
A moderate growing, rhizomatous perennial, reaching a maximum size of 5 x 4 feet. It is the hybrid of Rheum kialense & R. palmatum.
The very attractive, heart-shaped leaves are completely red during spring, later turning to glossy deep green ( veined red ) above, deep red beneath. They are borne on deep red stems. The foliage will turn yellow and go dormant during mid to late summer if drought occurs.
The reddish-pink flowers are borne on spikes up to 5 feet high. Hardy zones 3 to 6 ( mulch deeply during winter north of 4 ) in partial shade on moist, deep, fertile, well drained soil. They are preferrably grown on a site protected from excessive wind which can ruin the attractively oversized foliage.

Rheum acuminatum ( Sikkim Rhubarb )
A clumping perennial, reaching a maximum height of 3 feet, it is native to meadows at elevations around 12000 feet in the Himalayas.
The leaves, up to 12 x 10 inches, are glossy deep green above, purple beneath.
The leaves are borne on scarlet-red stalks.
The reddish-pink flowers are borne on panicles, up to 3 feet high, during early summer.
The flowers are followed by attractive red fruits.
Hardy zones 6 to 8

Rheum alexandrae
A clumping perennial, reaching a maximum size of 5 x 3.5 ( rarely over 3.3 ) feet, that is native to the Himalayas from the Tibetan Plateau to western China.
The deeply-veined, lance-shaped to ovate leaves, up to 12 x 8 inches, are glossy green above sometimes turning intense deep orange during autumn.
The flowers are borne on spikes up to 18 inches in length, during late spring.
The small flowers are hidden behind large showy bracts that are pale yellow aging to red.
Hardy zones 5 to 8 in full sun on very fertile, moist soil.

Rheum australe
A huge perennial, reaching a maximum size of 10 x 8 feet, that is native to the Himalayas.
The large, heart-shaped leaves, up to 40 inches across, are reddish-green with red veins.
The yellow to reddish-green flowers are borne on stalks up to 4 feet high, during late spring into early summer.
The stems are red.
Hardy zones 4 to 6 in full sun to partial shade, it is much more drought tolerant in partial shade. It can be propagated by dividing the clump while dormant.

Rheum compactum
A handsome perennial, reaching a maximum size of 3.5 x 3 feet, that is native to eastern Siberia.
The wavy-margined, heart-shaped leaves, up to 18 inches across, are glossy green.
The flowers are white.
Hardy zones 5 to 7 in full sun to partial shade.

Rheum x culturum
This is the edible Rhubarb.
The white flowers are borne on showy plumes during early summer. The flower stalks are usually removed to add more energy back into the clump.

* photos taken on July 1 2014 in Columbia, MD

* photo taken on on July 30 2014 in Columbia, MD

* photos taken on Apr 21 2015 in Columbia, MD

* photo taken on May 20 2015 in Columbia, MD


Rheum kialense
A rare but beautiful perennial, reaching a maximum height of 2 feet, that is native to Sichuan province in China. It makes an excellent, fast growing, dense groundcover.
The pleated triangular leaves, up to 4 inches in length, are reddish-green.
The reddish-green flowers are borne on stalks up to 8 inches high during early summer.
Hardy zones 5 to 9

Rheum officinale
A stately perennial, that is native to Tibet and western China.
The foliage is poisonous but the young leafstalks are edible and are often used to add flavoring to strawberry pie.
The very large, lobed leaves, up to 30 inches across, are luxuriant mid-green
The white flowers are borne on very tall stalks up to 10 feet in height.

* historic archive photo


Rheum palmatum
A clumping perennial, reaching a maximum size of 10 x 7.5 feet, that is native to northwest China. Plants may go dormant during the later half of summer in hot summer regions.
It looks spectacular next to a pond or water feature.
The huge, deeply-cut leaves, up to 36 x 40 inches, are purplish-red at first, turning to glossy deep green.
The fluffy, small, deep red flowers are borne on erect panicles, up to 3.3 feet in length, during early summer.
Hardy zones 4 to 6 in full sun ( where summers are cool ) to partial shade on very fertile, moist soil. Japanese Beetles may damage the foliage.

* photo taken on Sep 6 2012 in Harford Co., MD

* photo taken on Oct 17 2013 in Harford Co., MD


'Atrosanguineum'
Reaches a maximum size of 10 x 8 feet, with huge leaves up to 3 x 3 feet.
The spectacular foliage is intensely red at first, before turning to glossy deep green.
The deep red flowers are borne late spring to early summer.

'Bowles Crimson'
Foliage is deep red beneath, otherwise identical to species.

'Hadspen Crimson'
A gigantic stately perennial, reaching a maximum size of 10 x 10 feet.
The huge leaves, up to 40 inches in length, are deep red at first, later turning to reddish-green.
The giant red flower stalks reach up to 15 feet in height and bear creamy-white flowers.

var. tanguticum
A bold perennial, reaching a maximum size of 7 x 8 feet.
It looks great combined with variegated Solomon's Seal.
The huge foliage is deep purple at first, turning to deep green, then to deep red in fall. The foliage remains purple beneath throughout the season.
The rosy-red flowers are borne on pyramidal panicles during late spring.
Hardy zones 3 to 6

Rheum rhabarbarum ( Garden Rhubarb )
A perennial, that is commonly used as a vegetable. The foliage is poisonous but the young leafstalks are edible and are often used to add flavoring to strawberry pie.
In temperate climates, it is a herbaceous perennial that dies back to the ground after the first autumn frost, to then reappear during spring. In very mild climates, it may grow all year. Garden Rhubarb has been known to thrive as far north as the southwest Yukon and Atlin, British Columbia.

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