What is a colchicum?
Large-flowered colchicums flower without their leaves throughout autumn, offering an injection of colour. The Colchicum flowers vary in colour from white to pale pink and dark purple and can be narrow and slim to large and sturdy goblets on sturdy stems. There are multi-petalled colchicum selections in white and purple.
During the 20th century the great gardener and author EA Bowles championed the genus in his book A Handbook of Crocus and Colchicum for Gardeners published in 1924 with a revised edition in 1952.
Bowles was a stickler for correct nomenclature and often bemoaned the fact that colchicums were so inaccurately named. The underlying challenge for botanists is the seasonal difference of colchicum flowers in autumn and leaves in spring.
The cultivar Colchicum ‘Autumn Queen’, a fine early flowering, well-marked cultivar, is now well over 100 years old. Today there are about 70 named colchicum cultivars and 35 autumn-flowering species. Many of the species are difficult to grow.
There are also spring-flowering, mostly species colchicums. Colchicums are large, cormous plants with brown tunics that mainly flower in autumn. Commonly known as naked ladies, autumn crocus, and in the USA as false autumn crocuses, which is more accurate.
Origins Asia and Europe, usually in high-altitude meadows.
Size Colchicum flowers 10-30cm tall in autumn, leaves as tall and spreading in spring.
Conditions Sunny or half-shady position in borders and shrubberies, ideal in long grass, which is only mown from June until the end of August.
Hardiness rating Most have a rating of RHS H5 and are suitable for gardens in USDA zones 4a-8b. Holds an Award of Garden Merit from the Royal Horticultural Society. Hardiness ratings given where available.
The best colchicums for your garden
Colchicum ‘Autumn Queen’
One of the first autumn-flowering colchicum cultivars to flower. Often nosing through in late August with mid-sized flowers, which thrive in a sunny site. 18cm. AGM. RHS h5, usda 4a-8b.
Colchicum x agrippinum
This highly tessellated colchicum selection is a hybrid of unknown parentage. It has hybrid vigour with demure leaves in spring. 10cm. AGM. RHS H4.
Colchicum byzantinum ‘Innocence’
An albino cultivar, singled out from a Colchicum byzantinum bought from Van Tubergen nursery in the 20th century, Vigorous and floriferous. 15cm. AGM. RHS H5.
Colchicum ‘Benton End’
A substantial colchicum flower of quite a dark purple. It was found in the eponymous Suffolk garden of the artist Sir Cedric Morris, who was famed for his bearded irises. 18cm.
Colchicum ‘Pink Goblet’
Found by Dick Trotter in his garden Brin near Inverness. This