Friday, December 30, 2011

Roscoea

A genus of perennials that are part of the larger Ginger family. The orchid-like flower are borne on short spikes during summer. These plants go dormant autumn through spring. The bright to mid-green foliage often dies down and goes dormant by late summer if drought occurs. Mulch thickly in colder regions during winter...however the fleshy tuberous roots can also be lifted and stored in a cool, dark basement or garage during winter. They often appear late during spring waiting for some real warm weather to arrive, once they emerge they grow rapidly.
These plants prefer partial shade and woodland conditions. Native to summer monsoon climates, they prefer well drained soil that is moist during summer and not too wet during winter. Older clumps can be divided during early autumn. The rhizomes ahould be gently handled and planted at least 4 inches deep to protect from excessive freeze/thaw. Propagation from seed can be achieved by planting in trays of sand immediately upon ripening then storing in an unheated greenhouse over the winter. They should emerge the following spring.

Roscoea alpina
A perennial, reaching up to 1 foot x 5 inches, with pink to purplish flowers borne late spring into early summer. It is native to high mountains from Pakistan to southwest China.
The clumps of lance-shaped leaves appear late in spring.
It is native from Kashmir to Bhutan in the Himalayas.
Hardy zones 7 to 9 ( 6 on protected sites ) in partial shade.

Roscoea auriculata
A tuberous perennial, reaching up to 2 x 1 foot, that is native to Nepal and India.
The arching, broad lance-shaped leaves are deep green.
The purplish flowers are borne late summer into autumn.
Hardy zones 6 to 9 in partial shade on moist, fertile, humus-rich, well drained soil. Propagation is form division during early spring.

Roscoea beesiana
A vigorous perennial, reaching up to 1.5 x 1 foot, with yellow flowers that are tipped lilac-purple. It may be a hybrid between Roscoea. auriculata and R. cattleyoides.
The arching lance-shaped leaves are deep green.
Hardy zones 6 to 9 in partial shade on moist, fertile, humus-rich, well drained soil. Propagation is form division during early spring.

Roscoea cautleoides
A perennial, reaching up to 2 x 1 foot, with large, pale yellow, hooded flowers during early to mid-summer.
It is native to southwest China.
The sword-shaped leaves are blue-green.
Hardy zones 6 to 9 ( 5 if planted deep on protected sites with deep winter mulch ) in dappled or partial shade on fertile, peaty, well drained soil. It is hardy through most of the British Isles.

* photo of unknown internet source


'Kew Beauty'
Vigorous, with very large, creamy-yellow flowers borne on a shorter stem.
The leaves are broader than the species.

Roscoea humeana
A perennial, reaching up to 20 inches x 1 foot, bearing large flowers that are violet-purple ( with a yellow throat ) during late spring into early summer. It has the largest leaves of all the Roscoea, up to 2.8 inches wide, forming a clump up to 20 inches high.
Hardy zones 6 to 9

Roscoea purpurea ( Purple Roscoea )
A vigorous perennial, reaching up to 2.5 x 1 ( rarely over 1.5 ) feet, bearing large, rich purple flowers, up to 3.2 inches in size, during mid to late summer.
It is native to the Himalayas.
The arching, lance-shaped leaves, up to 10 ( rarely over 6 ) inches in length, are mid-green. It is late to break dormancy often not emerging until early summer, so it is best to plant with earlier spring bulbs such as Crocuses.
Hardy zones 6 to 9 ( 5 if planted deep on protected sites with deep winter mulch ) in dappled or partial shade on fertile, peaty, well drained soil. It can take sun in cooler climates as long as the roots are shaded and moist.

'Procera'
Vigorous in habit, otherwise similar.

Roscoea thibetica
A slow spreading, long lived, rhizomatous perennial, reaching up to 8 inches in height; that is native from India to western China ( Yunnan, Tibet and Sichuan ) as well as Burma.
The leaves form rosettes.
The deep purple flowers are borne on terminal spikes, during mid to late summer.
Hardy zones 6b to 9 in partial shade on consistently moist, well drained soil that is mulched. A rock garden is the ideal spot to try this beauty. The brittle, fleshy roots do not like disturbance including transplanting. Transplanting if necessary should be done in autumn in mild climates, early to mid spring in colder climates. For propagation - collect seed during autumn, store it in a fridge, then plant out during spring.

Roscoea wardii
A slow spreading, long lived, rhizomatous perennial, reaching up to 1 foot in height; that is native from India to western China ( Yunnan and Tibet ) as well as Burma.
The leaves form rosettes.
The deep purple flowers are borne on terminal spikes during early summer.
Hardy zones 6b to 9 in partial shade on consistently moist, well drained soil that is mulched. The brittle, fleshy roots do not like disturbance including transplanting. Transplanting if necessary should be done in autumn in mild climates, early to mid spring in colder climates. For propagation - collect seed during autumn, store it in a fridge, then plant out during spring.

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