The giant Himalayan lily (Cardiocrinum giganteum) is a little-known member of the lily family. This rhizomatous perennial belongs to a small genus containing two other species. Only a small number of them are planted in the garden here at Harlow Carr. However, the plant itself is far from small.
C. giganteum or the ‘Giant Himalayan Lily’ is native to the Indian Himalayas, Tibet, Nepal, Bhutan, Pakistan, China and Myanmar (Burma), growing at elevations of up to 3600m (1200ft). Essentially a big bulb, it has a huge basal rosette of large, heart-shaped, glossy, dark green dinner plate-sized leaves each 30cm (12in) in length. These are often bronze/purple tinged when young.
Flowering June to August, its thick flower stems erupt from a huge rosette reaching an impressive 1.5 to 4m (5–13ft) in height, each bearing racemes of 20 to 40 large white, powerfully fragrant trumpet-shaped flowers 15-20cm (6-8in) long, with maroon stripes inside. In late September, attractive oblong seedpods form, making attractive decorations if kept and dried.
This plant towers above its neighbours, and can be found planted in a prominent position at the top of the newly planted Peat Terrace. Like other members of its family, this genus is intolerant of hot, sunny exposures, where the foliage is liable to burn and instead must be planted in sheltered woodland conditions, in cool dappled shade with deep, fertile humus rich soil.
It is well worth preparing the soil prior to planting by adding plenty of leafmould or compost. During the flowering period it is best to feed with bone meal and kept well watered during dry periods. As a member of the lily family this plant is very susceptible to lily beetle damage, and being a bulb it is also very attractive to slugs, mice and voles and may require protection.
These plants make a valuable, high-impact addition to any woodland garden, offering height and structure. Once established and planted in the correct conditions they thrive, forming large towering groups. We think they look great planted among other woodland plants such as Epimedium, Erythronium and Trillium.
Two failings of these superb plants are their rarity in cultivation, with only a limited number of specialist plant nurseries that stock them, and their very slow rate of growth. So if you are lucky enough to source good plants, it would be best to propagate them yourself. Cardiocrinum giganteum can be propagated in two ways, either by offsets (new bulblets) or seed.
The quickest way to achieve flowering is to take offsets – do this by removing these naturally occurring bulblets from the parent bulb in October after the top growth has died back. These small plants can be potted on, and will take three to five years to reach flowering size. Plants propagated from offsets will never grow taller than 1–1.5m (3–5ft).
To propagate plants that will reach impressive 1.5 to 4m (5-13ft) you will need to propagate from seed. Propagating from seed takes longer but results in a taller plant. Sow Cardiocrinum giganteum seeds from February to July, on the surface of pot of compost. Cover with 1.5mm (0.05in) of compost or Vermiculite and keep the soil damp but not wet. Germination can be very slow, with plants taking seven years to flower – compost should be kept moist at all times.
Cardiocrinum giganteum is a truly impressive plant and well worth growing. C. giganteum var. yunnanense 'Giant Yunnan Lily' is a particularly good variety. Plants can be sourced from specialist nurseries such as Crûg Farm Plants or Burncoose Nurseries. C. giganteum is the most widely grown in cultivation and new species are made available all the time C. cordatum and C. cathayanum have only recently become readily available.
Despite its slow growth rate, this rare beauty is well worth the wait.
Find out about forthcoming events at RHS Garden Harlow Carr
More plants that love a shady woodland setting
Unearth suppliers of Cardiocrinum with RHS Find a plant