The genus Bletilla comprises nine or ten species of terrestrial orchid that are native to China, Japan, Taiwan and other east-Asian countries. It is sometimes confused with Bletia, an unrelated genus of about fifty species with similar flowers; however the genus Bletia is found only in the Americas.
Bletilla striata is the best known of the bletillas, being found not only in orchid collections but also in many gardens around the world. Arguably, it is the easiest of all orchids to grow in cultivation. It is very adaptable, being suited to both cool (frost-free) and warm conditions. Bletilla striata produces a stem bearing a cluster of light green, pleated leaves up to 500 mm tall during winter. In spring a single inflorescence emerges from the centre of the leaves. It reaches a height of 600 mm and bears up to twelve (usually less) showy, nodding flowers; they do not always open fully. The rose/magenta flowers measure 30-40 mm across and have a darker-coloured lip bearing five parallel keels.
While the pseudo-bulbs of Bletilla striata resemble the corms of some bulbs, they differ from those of many terrestrial orchids. They are slightly compressed, rounded, and always found just below the surface of the ground. The deciduous plants multiply vegetatively each year, and are therefore best grown in rather large pots (200-250 mm in diameter). A good potting mix containing loam, leaf mulch and sand, with the liberal addition of fertiliser, is required. It should drain well and last for three or four years, as the plants do not like disturbance. After the leaves have died, the pots should not be watered for a few weeks, so that the pseudo-bulbs can ‘rest’. The plants resume growth in winter and flower in spring. Apart from occasional misting, water should be withheld until the new leaves are well formed. Liquid fertiliser may then be applied. In fact, bletillas seem to benefit from the application of fertiliser each time they are watered.
The plants are best re-potted in autumn after the leaves have died down. The pseudo-bulbs may then be removed, and some of the old mix carefully shaken from them. Re-pot in new potting mix with as little disturbance as possible. Sometimes the plants will not flower until they have become pot-bound. Small bulbs do not usually produce flowers. After a few years, natural multiplication provides an attractive specimen bearing a lovely display of purple flowers.
Bletilla striata may also be grown in the garden, preferably in a bed where its plants will be partly shaded and free from disturbance for a number of years. Most general gardeners know it only by its common name, the Chinese ground orchid.