Windowsill magic: fall-flowering colchiums

Flower & Garden Magazine, August-Sept, 1996 by Joan Hustace Walker

What Would You Say To A catalog's description of a bulb that can be brought into bloom on a windowsill, with no water, soil or effort? Any indoor gardener might be skeptical of these claims; however, the fall-flowering bulbs known as colchicums are every bit as beautiful and easy to bloom as catalogs declare.

Colchicums are commonly called autumn crocuses. One variety, 'The Giant,' does indeed resemble a large crocus, but it shouldn't be confused with the autumn-blooming members of the genus Crocus. Colchicums display a rather peculiar growing behavior, blooming well after the bulbs' spring foliage has matured and died. The effect is rather spectacular but also oddly stark, because the only thing the observer sees is a white stalk with rosy-lavender flowers protruding from the earth.

Colchicums require no special treatment to bloom indoors, so long as you follow the plants' natural schedule of growth and dormancy. Be sure to order your colchicums early. The bulbs (or "corms," to botanists) are shipped in late summer, typically during the last week of August or early September. Many garden centers also sell colchicum bulbs before their bloom season.

Immediately upon arrival, the bulbs should be removed from their shipping container and placed in a dish or pot, pointed end up. No soil or water is needed, so the "potting" possibilities are virtually limitless. If you've always wanted to plant something in that crystal biscuit jar, now is your chance!

Place the bulbs in a bright window. Within days, large, white growths will pierce through the dry, papery covering of the bulbs. As the shoots emerge, they branch into individual blossoms and take on a lavender color, beginning at the tips of the petals; it looks as if they are blushing. Normally, a colchicum will bloom within three to four weeks from the emergence of the first bud.

At room temperature, the colchicum blooms last about a week to 10 days. Keep in mind that the blooms wil1 direct themselves toward light, so be sure to rotate the container regularly to produce straight growth.

As soon as the blooms wither, plant the bulbs outdoors in a sunny or semishaded spot. Colchicums are hardy in Zones 4 to 9, and they'll reward you with autumn color for years to come. Put a little bone meal in the planting holes, then cover the bulbs with 4 inches of soil and a heavy mulch. The bulbs will not produce foliage until the following year in late spring. The leaves are similar to, but much thicker than, daffodil foliage. They may seem to take forever to die back, but don't cut the leaves prematurely; the foliage produces the energy needed for the bulbs to bloom.

Of course, you can bypass the indoor flowering and plant your purchased colchicums directly in the garden; they'll bloom this fall. In future years, if you wish to dig colchicums from your garden to bloom indoors, mark locations of the bulbs as the foliage withers naturally. Wait until late August or early September to dig the bulbs.

Editor's note: Sources for colchicurns are listed on page 81.