Dahlias, the Awesome Flower
By Bob Chapman
Dahlias originated in Mexico and Guatemala and were named after Dr. Anders Dahl (1751-89) a Swedish botanist. Since their discovery and naming, dahlias have been hybridized extensively and are found in gardens throughout the world, blooming profusely in summer. These strong, tender herbs grow from underground tubers and varieties are known that range in form from tall and tree-like to the smaller, almost dwarf sizes.
The flowers are very diversified in form or shape and are found in all colors except blue. Dahlia fanciers developed and grew so many exotic flower forms in the two hundred and fifty years since being introduced by Dr. Dahl that it became almost impossible to keep track of them. Banding together, dahlia enthusiasts formed the American Dahlia Society to promote the development, knowledge about and spread of this very popular flower.
Plant dahlias in full sun. Most dahlias prefer soil that is well drained and with lots of organic matter, although they have been known to grow in most soils found in the world. Plant the tubers of the taller types about one foot deep, those of the dwarf types about nine inches deep. Fertilize at the time of planting with a half-cup of a low-nitrogen fertilizer.
Divisions or categories of dahlias
A system of categories or divisions was developed to differentiate the many flower forms. When looking at the colorful flowers below, you begin to appreciate the glorious colors and forms.
Division 1:
Single flowering.
Distinguishing characteristics: one ring of florets,
central group of disc florets.
Height of plant at maturity:18-24 inches.
Division 2:
Anemone-flowering.
Distinguishing characteristics: One or more rings
of florets, central group of tubular florets. Height of plant at maturity 24-36 inches.
Division 3:
Colarette
Distinguishing characteristics: One outer ring of flat florets and an inner ring of collar florets, central group of disc florets.
Height of plant at maturity: 30-48 inches.
Division 4:
Water-lily
Distinguishing characteristics: Fully double, flattened shape, florets are flat with slightly curved margins.
Height of plant at maturity: 48 inches.
Division 5
Decorative
Distinguishing characteristics: fully double, flat florets are broad and blunt-ended
Height of plant at maturity: 60 inches.
Division 6
Ball
Distinguishing characteristics: fully double, ball-shaped (often flat), florets are blunt or round ended.
Height of plant at maturity: 48 inches
Division 7
Pompon
Distinguishing characteristics: fully double, globe shaped, involute florets are blunt or round ended.
Height of plant at maturity: 32-48 inches
Division 8
Cactus
Distinguishing characteristics: fully double, involute florets are narrow and pointed.
Height of plant at maturity: 60 inches.
Division 9
Semi-cactus
Distinguishing characteristics: fully double, pointed florets are involute for half their length or less.
Height of plant at maturity: 60 inches.
Division 10
Peony-flowering
Distinguishing characteristics: fully double, florets are round ended
Height of plant at maturity: 40 inches
Division 11
Mignon
Distinguishing characteristics; small flowers, 1 1/2 -3 inches, suitable for containers
Height of plant at maturity: 32 inches.
Division 12
Topmix
Distinguishing characteristics: small flowers 1 1/2-2 inches, suitable for containers.
Height at plant maturity: About 14 inches.
Three new groups
Hybridizers have been developing dahlias suitable for container growing and use as bedding plants. The following are descriptions of these newer dahlias and describes how they can be distinguished.
• Dahlianova types
Double flowering varieties in every color except blue. Growing to only 8-12 inches
• Gallery series
Contains the cactus and decorative varieties growing no higher than 12-14 inches.
• Impression selection
These are colarette dahlias, used primarily for bedding and containers on patios. Depending on the variety these dahlias grow to 12-20 inches in height.