There are literally thousands of cultivated varieties of dahlias, which have been hybridized throughout the years.
Dahlia plants range in height from as low as 12 inches to as tall as 6 to 8 feet, and the flowers can be as small as 2 inches or up to 1 foot in diameter.
Some specimens may provide an abundance of cut flowers for the home, while others give you the opportunity to make a bold statement in your landscape by pruning, disbudding and ultimately forcing the plant to create a few single, gigantic blooms.
Novice dahlia growers may want to start by selecting a few plants of varying colors, sizes and types. Once you've grown your first crop of these beauties, you will have a much better idea of which types to grow in subsequent years.
Treated properly, dahlias grow well in North Georgia and the state's piedmont area. To grow dahlias, consider first how much space you're willing to dedicate to them, since they grow up to 8 feet tall. Typical plants are 3 to 5 feet tall.
Most catalogs and specialist nurseries also classify dahlias as early, typical or late blooming and note whether they're best for cut flowers or exhibition blooms. For a more in-depth breakdown, consult the Dahlia Society of Georgia or the American Dahlia Society.
Dahlia tubers are typically sold in late winter and spring. Many mail-order nurseries accept orders until late spring.
Tubers are often planted in May in North Georgia. June plantings often give perfect fall flowers.
Dahlias thrive in the sun. They'll do best if they get at least a half-day of direct sunlight. And they need at least six to eight hours of direct light to produce good blooms.
The ideal soil for dahlias is one that's loose, holds moisture well and provides good aeration. The best pH is between 6.0 and 6.5. Dahlias are heavy feeders and develop large root systems. It's best to fertilize with liquid plant food every four weeks.
To plant dahlias, place the tubers 4 to 6 inches deep. Put the tubers on their sides with the eyes facing upward. Cover them with 2 to 3 inches of soil.
Be generous in spacing; some of the small bedding varieties can be spaced 12 inches apart but usually require a couple feet on each side. The larger varieties need three to four feet of space between plants.
When the young plant has produced three or four pairs of leaves and is several inches high, pinch out the tip. This will cause the shoot to branch and produce side limbs.
You'll be in for a big disappointment if you don't stake your dahlias; since many of the larger varieties grow tall, they can't support themselves when they reach maturity.
Make stakes 5 to 6 feet long and drive them about 1 foot into the ground. When the plants are about a foot tall, tie them to the stakes with soft string or cloth strips. Repeat about once a month as the plants grow taller — the limbs that bear the flowers especially need support.
Thanks to Paul Thomas, UGA Extension Horticulturist.
Billy Skaggs is an agricultural agent and Hall County extension coordinator. Phone: 770-531-6988. Fax: 770-531-3994.