Colchicum autumnale, generally recognized as autumn crocus, meadow saffron or naked lady, is a flower that resembles the true crocuses, but blooms in autumn. This is a very weird plant, and if you don’t know what to expect it can really fool you. The plant foliage comes up in spring, just like that of a spring bulb, but it doesn’t bloom, and by summer the leaves disappear. However, if fall, long after you’ve perhaps said; oh, well so much for Colchicum autumnale, some stems come out of the ground with no leaves on them, just big pink, lavender or white flowers that look sort of like large crocuses.
The species is usually cultivated as an ornamental in temperate areas, in spite of its toxicity. There nice as it is to have a fall blooming bulb, or fall blooming anything, you do have the problem of how to landscape those flowerless spring leaves and those leafless fall flowers. They are supposed to look great planted in front of shrubs, but this makes them look all the more gawky. Moreover, plant them in a natural setting, in sun or light shade, where there is a permanent, evergreen ground cover such as periwinkle, which will deemphasize both the leaves and their absence. They will also naturalize well in grass. Colchicum normally grows from corms and is hardy as well. Colchicum autumnale is the only species of its genus native to the Great Britain and Ireland, occurs across mainland Europe from Portugal to Ukraine, and naturalized in Denmark, Sweden, European Russia, the Baltic States and New Zealand.
So, Hybrids of C. autumnale grow about 8 inches tall. However, some colchicums sold are hybrids of C. speciosum. These are apt to be a hit taller. C. speciosum Album is white, despite the fact that these all look something like crocuses and are even called autumn crocuses in some catalogs. They are not the same as spring blooming crocuses which are another species altogether and have their leaves and flowers well synchronized. Moreover, Colchicum plants are deadly poisonous due to their colchicine content. Therefore, the symptoms of colchicine poisoning resemble those of arsenic, and no antidote is recognized.
Well, to grow Colchicum corms are sold in summer. So they should be planted in late summer or early fall in sun or part shade, about 8 inches apart. They are not fussy about soil, but add organic matter if yours is sandy or dry because they need a reasonable amount of moisture. Plant the large bulbs with the tops at least three inches below the soil surface. Though, bulbs normally multiply by themselves without human intervention. Source: CP