Growing Dahlias

Ten groups, or types, of dahlias are officially recognized by the National Dahlia Society, encompassing nearly 800 separate varieties of the diverse Compositae family. These groups, which are subdivided according to the diameter of their blooms, are as follows:

Group 1 Single-flowered dahlias
Group 2 Anemone-flowered dahlias
Group 3 Collerette dahlias
Group 4 Waterlily dahlias
Group 5 Decorative dahlias
Group 6 Ball dahlias
Group 7 Pompon dahlias
Group 8 Cactus dahlias
Group 9 Semi-cactus dahlias
Group 10 Miscellaneous dahlias

Identifying dahlia groups and varieties can be important not only for exhibitions, but also for cultivation in the garden or cut flower production.

"Although there has been a great deal written about the dahlia, much of it has been in journals of specialist dahlia societies, which are not widely available to the average gardener," notes dahlia expert Gareth Rowlands, who authored "The Gardener's Guide to Growing Dahlias" for the amateur dahlia enthusiast.

Rowlands' book gathers much of what is known about dahlias in a single, concise and beautifully illustrated text. The chapter on cultivation offers tips on planting, watering, feeding, spraying and cutting blooms. When disbudding for show, the author suggests removing all the side shoots down the flower stem to get the maximum size bloom.

"This is known as securing the bloom," he points out. "However, it is wise to leave at least one side shoot at the base of the flower stem so that when the bloom is cut, a replacement shoot can grow and produce a second flush of flowerheads. Growers should be aware that if the bloom is being produced for show purposes and the side shoots are removed too enthusiastically, the resulting flowerhead may grow oversize and be disqualified on the showbench."