Dahlias perform best in full sun and well-drained soil; they may rot in wet, poorly drained soils. Tuberous roots radiate out from the dahlia crown like the spokes of a wagon wheel. Viable tubers must have an eye originating from the crown portion, plus a neck that connects the crown to the body of the tuberous root.

For earlier blooming, plant dahlia tubers in 8-inch standard pots now. Fill pots about half-full with a commercial, sterilized potting mix or make your own by combining equal amounts of sphagnum peat, perlite, and sterilized soil. Place the tuber horizontally on the soil mix and cover with 1 to 2 inches of soil mix; water thoroughly. When growth emerges, place pot in full sun. Plants can remain in pots or be transplanted to the garden.

Frost can damage or destroy the plants so do not plant outdoors too early. Wait until May 5 to 10 in southern Iowa, May 10 to 15 in central Iowa, or after May 20 in northern Iowa.

Before planting, drive a sturdy support-such as a metal fence post or wooden stake-into the ground. Doing this prior to planting ensure that the tubers will not be damaged. To plant tubers, dig a hole about 6 to 8 inches deep on either side of the support. Place the tuber horizontally in the ground. Then place the soil back in the hole. The dahlias should emerge in about 2 weeks. A publication, PM 1925, is available on the Web .

This article originally appeared in the 4/16/2004 issue.