By George Koons
Central States Dahlia Society
The cultivation of new dahlia plants from last year’s crop is not a very complicated process. Many growers have their own preferred “small tweaks,” but the same basic process is followed by everyone. The annual cycle starts after the frost when the tuber clumps that grew during the season are “lifted” from the ground.
The tuber clump is cleaned and the individual tubers are separated. The individual tubers are then dried, labeled, and stored over the winter. In the second half of February, gardeners take the individual tubers from storage and start the propagation process.
After two to three weeks, the tuber “wakes up” and produces its first sprout. This is the beginning of the new life cycle of the tuber plant.
When the spout grows to about two inches, it is harvested by slicing it away from the tuber. The cutting is placed into a growing medium and starts to form its own root system. During this period, the cutting must be exposed to about 16 hours per day of light and kept moist. Dahlia hobbyists dedicate a section of their garages, basements, or attics to their dahlia “nursery.” Some are more sophisticated than others, but they all produce results.
After about two weeks, the cutting establishes its own root system.
The rooted cutting is then planted in a small pot that contains the type of soil in which the plant will eventually spend its summer growing period.
These are the plants that will be sold at the Central States Dahlia Society’s May plant sale at the Chicago Botanic Garden in Glencoe. By that time, they will be about five inches tall. They will be ready to go into the ground as soon as the soil temperature remains above 50 degrees. In the Chicago area, this could be as early as the middle of May.
Conservative gardeners will wait until the end of May before planting their stock. Dahlia plants will grow to a height of five feet or more. So the plants must be supported. The stakes should be put in the ground at the same time as the plant. Doing this later may disturb the root system. Plastic garden stakes from a nursery can be used. However, these are not very durable. So most dahlia gardens head off to their local building supply and buy cut lengths of 3/8 inch rebar.
Depending on the variety, dahlia blooms will range from two to ten inches in diameter. The largest sizes, classified as AA, are called “dinner plate” dahlias.
With proper care and the cooperation of Mother Nature, the plants should produce their first flush of blooms by the end of July. They will continue to bloom until the first frost; at which time, the cycle starts all over once more.
Dahlias are fantastic cut flowers for the table. One wonderful characteristic of these plants is that the more you cut, the more they bloom. So you will have a house full of flowers for three or four months. Your flower bed will be enjoyed by neighbors and passers-by.