Wachendorfia are tuberous evergreen perennials which grow wild on grassy slopes in South Africa. W. thrysiflora is the only species which is commonly grown in more frost free coastal gardens in the west of England. At Caerhays a clump is just beginning to naturalise itself and bulk up in a hot sheltered spot facing east and backed by a stone wall which reflects the summer heat into the dry ground.
W. thrysiflora has unusual furry red roots and tubers. It has upright gladiola-like leaves which are a dark green and fairly brittle but, in maturity, can extend to around 3ft in height.
In late May or June this plant produces a single tall leafless flower spike which is often up to 5ft tall here in the Burncoose show tunnel. The top of the spike produces dense panicles of star shaped yellow flowers. The flowers at the base of the spike are normally over before the buds open further up the stem. In a larger clump, with more than one flowering spike, the flowers from the more immature tubers seem to grow and open a week or two after the principal and largest flower spike.
In colder or frost prone areas this attractive plant can easily be grown in a large pot and placed outside for the summer months before returning to the greenhouse for the winter. A rich compost is recommended with additional sand, peat and leaf mould to improve drainage. Keep moist when dormant in winter but do not overwater then.
The plant can readily be propagated from the plentiful seed which it sets after a hot summer. The seed can be sown under glass in the autumn or spring. The tubers can be gently divided and separated in early spring. Slugs or snails can be a problem even in the greenhouse.
