Rheum australe aka Himalayan Rhubarb

Rheum australe is a large perennial in the knotweed family, Polygonaceae. Gardeners know it as Himalayan rhubarb or Nepal rhubarb. Its native range runs from northern Pakistan to northern Myanmar. It grows in cold mountain regions on rocky, open slopes. It also grows on grassy slopes in Tibet. The plant forms a clump and spreads from rhizomes. Its leaves die back at the end of the season.

Garden plants reach about 5–8 feet [1.5–2.5 metres] tall and wide. They need space for their broad leaves and flower stems. The oval or round leaves emerge in late spring. They reach about 2.5 feet [0.75 metres] long. Their edges ripple, and coarse hairs cover their undersides. Thick, reddish leaf stalks hold the green blades. Young leaves may look bronze, then gain red tones in autumn. Tall, branched stems carry dense groups of small, drooping flowers. These purplish-red blooms appear in June and July.

Grow this plant in deep, rich soil that stays moist. Good drainage matters, since poorly drained soil can cause crown rot. It accepts clay or loam with acid or neutral pH. Full sun suits it best, though it also accepts partial shade. Add an organic mulch in early spring. Cut away faded leaves when the growing season ends. Divide clumps in early spring, or sow seeds in autumn. Plants reach full size within two to five years. RHS rates its hardiness H6; Missouri Botanical Garden lists USDA zones 5–7.

Its large leaves give beds and borders a bold shape. It also suits planting beside streams and ponds. Missouri Botanical Garden reports few serious pest or disease problems. Slugs, aphids, borers, beetles and rhubarb curculio may still attack it. Other possible diseases include honey fungus and viral infections. The plant resists rabbits, according to Missouri Botanical Garden.

Plants For A Future lists the leaf stalks as food. They can be cooked, preserved or dried for later use. This does not make the whole plant safe to eat. RHS warns that it can harm both people and pets. Keep that warning distinct from reports of edible stalks. The roots have a history of use in herbal medicine. They also yield a yellow dye. People have used the broad leaves to line baskets and protect fruit.