Growing and Caring for Dahlia Flowers

Dahlias, which can grow as either annuals or perennials, are plants that produce striking colorful flowers. These easy-to-grow plants make excellent flowerbed additions as their flowers come in one of the widest range of shapes, sizes and colors of any garden flower. Dahlia flowers are all colors except for true blue and some dahlias have striped colors or tips of a different color. Besides their beauty, they’ve even been used for medical purposes such as treating diabetes, as diabetics were once given a diabetic sugar made from dahlia tubers.

Size of Dahlia Flowers

Dahlias range in sizes from mignons that are only two to four inches long to to large flowers that are more than ten inches wide, according to Planting Flower Bulbs.com. Although giant varieties (over ten inches wide) take longer to bloom, smaller varieties are used more in bouquets and floral arrangements.

Considerations Regarding Dahlia Flowers

Flower production may be slower when summer temperatures are high and plants are stressed for moisture. Dahlias do best in well-drained humus rich soil and full light. Although they can’t take cold temperatures, they do benefit from cooler climates with much rainfall. They bloom from mid-summer through the first frost and can look even more spectacular in cool weather.

Petal Arrangements of Dahlias

Dahlias are classified by their petal arrangements and shapes. Single-flowering dahlias have a single row of petals, while anemone dahlias have an additional ring of small petals. Orchid-flowering dahlias have ray florets that curl upward along edges and collarette dahlias have only one outer ring of ray florets that lay basically flat.

Decorative dahlias have full double blooms without a disc, while ray florets are wide, mostly flat and slightly twisted. Ball dahlias are somewhat flattened and ball-shaped with full double blooms. Pompon dahlias are similar to ball dahlias, but are smaller and more globular. Cactus dahlias have full double blooms with ray florets that are typically pointed, while the semi-cactus variety has ray florets that are wider than cactus dahlias.

Diseases and Pests of Dahlias

Bacterial wilt causes wilting and stems to drop. Infected stems show a soft wet rot near the soil. Bacteriosis, which is linked with a foul odor, causes stem softening and browning. It causes the pitch to blacken and become moist with the rot going into bark. Botrytis Blight or gray mold is a fungus occurring during high humidity.

Common pests are aphids, mites, slugs and deer. Aphids and slugs are the first pests to appear in a growing season, while mites emerge from mid-summer to late-summer. Other pests that sometimes attack dahlias are thrips, caterpillars, earwigs and wasps.

History of Dahlia Flowers

Dahlias were first discovered by the Toltec tribes of Central Mexico. An herbal that was recorded around 1550 was rediscovered in 1929 which included proof that dahlias were used for treating epilepsy. The plant was named the ‚”Dahlia” plant genus for Andreas Dahl, who was a famous Swedish botanist who studied under Carl Linnaeus, who created a system for classifying organisms still used today. Popularity of dahlias increased during the 1800s as thousands of varieties were found and documented. At first dahlia tubers were used as a food crop for supplementing potatoes, but later it was decided they’re suited more for decoration rather than food.

Finally, gardeners new to growing dahlia flowers can enjoy experimenting with the different varieties. If their first attempts of growing dahlias aren’t quite what they expected they can easily try another variety, especially if they grow dahlias as annuals. Because these flowers come in so many different colors, heights and forms, they offer a novice gardener many choices.

Resources:

Planting Flower Bulbs: Information About Dahlia Flowers (date accessed 4/7/2010)