Overview


Colchicum

Autumn is my favorite time of the year.   Warmth lingers but stifling heat departs, as the temperature moderates.   Maple, dogwood, and scarlet oak flame up in crimson, vermillion, and (of course) scarlet.   Elm, witch hazel, and birch bring brilliant yellow foliage that moves like liquid sunshine in the breeze.    And Colchicum burst forth from the ground in an array of colors to cheerfully greet the cooler days.

Every gardener should have colchicums or autumn crocus as they are often called.   The blossoms are superficially similar to true autumn crocus ( Crocus sp.)   Both have low growing flowers in purple, pink, and white shades.   However, their bulbs (actually corms) and leaves are very different; and although colchicum and crocus are monocots, they are in entirely different plant families.

crocus and colchicums

For the sake of gardening though, they are both great plants for the autumn garden.   Colchicums usually have larger, showier flowers.   Here in Chicago I have had more success with colchicum.   They withstand Winter and naturalize well.   The two advantages for colchicum over autumn-blooming crocus are showier flowers and the defensive chemical colchicine.    Squirrels, voles, and field mice love crocus.   I have watched squirrels watch me planting crocus; and later found the area dug and disturbed.   Colchicums produce the toxin, colchicine, so nothing eats them---except (there's always an "except") vile slugs and snails.   These mollusks are rarely a problem in my garden, but this could be a serious issue in the Pacific Northwest where you have slugs the size of potatoes.

Horticulturally, colchicums are easy to grow.   They are not particular about soil.   Average moisture is fine.   Partial shade to full sun will give good results.   However, design-wise they can be tricky.   The broad, tulip-like foliage appears in Spring and withers in early Summer.   Flowers sprout from the bulb at ground level in Autumn.   Colchicums should be placed where they are relatively inconspicuous in Spring and on full display in Autumn.    Planting the bulbs within low groundcovers is a standard solution.

The bulbs are relatively expensive.   Fortunately, there are several flowers per bulb and they multiply at a good pace.   The common varieties are available at most garden centers.   C . "The Giant" and C . "Lilac Wonder" are proven cultivars and the most popular.   Specialty nurseries and mail order catalogs offer a wide variety of colchicum species and their cultivars, including : C. autumnale , C. speciosum , C. byzantium .    The double flowered cultivars C . "Waterlily" and C. autumnale "Alboplenum" are dazzling blossoms, perhaps the most incredible flowers of Autumn.

	In my raised meadow garden C. byzantium faithfully blooms around the autumnal equinox.   The rosy flowers are abundantly produced over a couple of weeks.   This is one of the most floriferous varieties. In my observation the larger flowered colchicums have fewer blossoms than the smaller flowered ones. Double flowered cultivars seem to produce the fewest, but then they are the showiest.
In large spaces colchicums should be mass planted under ornamental trees or tall shrubs.   This is the setting where the plant reaches its full glory.   Seeing dozens of bulbs clustered together profusely blooming in succession is an unforgettable site.   Those with small gardens can still enjoy a great display with a few of the double flowered cultivars.   Colchicums are heralds of changing seasons and a welcome addition to any garden.