Culture
Easily grown in average, medium moisture, well-drained soils in full sun to light shade. Best in deep, humusy soils. Plant corms 3” deep and 6” apart in August for bloom the same year in fall. If necessary, dig and divide during the mid-summer dormant period. Will naturalize over time.
Noteworthy Characteristics
Colchicum is a genus of about 45 species of plants from alpine and subalpine meadows and hillsides in Europe, North Africa, West and Central Asia, North India and West China. Many are called autumn crocus because they bloom in fall but some species bloom in winter or spring. Species flowers can be purple, pink, lilac, yellow or white. In late spring, each autumn crocus corm sends up a clump of basal foliage (4-6 lance-shaped, dark green leaves to 14” long). Foliage gradually yellows and dies by summer as the plants go dormant. Naked flower stems rise from the ground to 4-6” tall in late summer to early fall bearing goblet-shaped flowers (to 3” long).
Genus name come from the abundance of the plant in Colchis, the Black Sea region of Georgia, Caucasus.
The "crocus" part of the common name for this plant is misleading, because autumn crocus is in the colchicum family whereas spring crocus is in the iris family. Autumn crocuses produce foliage in spring (foliage dies by summer) and flowers in fall (each having six stamens and a superior ovary). Spring crocuses produce both foliage and flowers in spring, with each flower having three stamens and an inferior ovary. Plants in the genus Colchicum are also sometimes commonly called meadow saffron or colchicum which avoids the crocus name confusion. Colchicine is extracted from seeds and corms of genus plants for medical use in the treatment of gout and for horticultural use in the hybridization of plants and chromosome doubling.
'Disraeli' is an old Colchicum cultivar with unclear origins. It may be a cross between Colchicum giganteum and Colchicum speciosum bornmeulleri or have originated from Colchicum bivonae. Most sources do agree that it is of Dutch origin. 'Disraeli' has bright rosy purple, tulip-shaped flowers that are produced in clusters close to the ground. The flowers have a white center, tessellated or checkered petals, and purple anthers. 'Disraeli' grows 0.5 to 0.75 ft. tall and wide.
Problems
No serious insect or disease problems. Watch for slugs and snails. Botrytis is an occasional disease problem. Corm rot is a concern in poorly-drained wet soils. Weak flower stems tend to flop. All parts of plants in the genus Colchicum are toxic to humans, especially the seeds and corms. Gloves should be worn when handling the corms to avoid possible skin irritations.
Uses
Meadows, woodlands, beds, borders or rock gardens. Good for pockets in the landscape where spring and summer plants are fading. Good around patios or along walks. Plant with low ground covers that may help support weak flower stems. Generally inappropriate for prominent parts of beds or borders because of the unsightly appearance of the spring foliage as it yellows and declines on its way toward summer dormancy.