Colchicum or Autumn Crocus? What should you plant?

 Colchicum always surprise me. I mean, I know where I planted them, and I know when they are supposed bloom, but I am never really prepared for when they emerge, which seems to be virtually over night. All it takes is a few chilly nights in September, and suddenly, a sea of purple opens up driving the bees, crazy. Last Saturday morning, I noticed some of my populations blooming even nicer than the week before ( when I had mistakenly believed that our Indian Runner Ducks had extracted each of the early blossoms). One week later, the clumps looked not worse for the wear, and in the late summer sunshine, opened up their petals for a magnificent show.

1. Order Early.
The ‘Waterlily’ Colchicum above are an impressive display at the Tower Hill Botanic Garden. It demonstrates the best way to site these autumn flowering bulbs. There are a few things to remember, First, plant Colchicum early, which means that you must order them early.

2. Site them where they will look awesome in September.
This is important for two reasons. First, Colchicums bloom immediately after planting in the autumn, but they send up their foliage in the spring, which can be rather aggressive. The foliage is not unattractive, but it dies down in early July, so plan for this ( combining Narcissus is a good idea, but not Hosta, for when the plants bloom in the fall, you will not see them). The idea location, is an open spot in a mixed shrub border, which remains bare as above.

3. Plant lots of bulbs
If you order from a major retail mail order source, they will arrive at the proper time to plant for your zone, but like all bulbs, the more you plant, the better the display. I calculate that the drift of ‘Waterlily’ colchicum at Tower Hill came from about 50 bulbs, planted about ten years ago. Even 25 bulbs plants 1 foot apart, will give you the same look in 3 years. These are plants that become better with age, so feel good about investing in them.

4. Here is the confusing part. The common name for Colchicum is ‘Autumn Crocus’, but they are not true Autumn Crocus, for there are many species of true crocus which are autumn blooming, and most look very much like spring blooming crocus which you surely know. The genus crocus is not related to the genus Colchicum, and out of the 80 or so species of true crocus, about half are autumn blooming. Sadly, many true autumn crocus are not hardy beyond Zone 6, and collectors tend to grow crocus in greenhouse collections.  You may have heard that Saffron comes from Crocus, which it does, an autumn blooming one, Crocus sativus.
 
Colchicum are a different genus, and, not all Colchicum are fall blooming, some species bloom in winter, and others in the spring.  There are many named varieties which are very old to culture, but the pure wild forms, or species number around 60. Most are native to Turkey, the Middle East and Southern Russia. These are generally collector species, and only a few micro collector nurseries carry the spring bloomers, so don’t worry about getting anything but a fall blooming Colchicum from your local garden center, or from a Dutch bulb dealer.