Common name: Dahlia

Botanical name: Dahlia x. hybridus

Trivia: Named for Dr. Anders Dahl (1751-98), a Swedish botanist and pupil of Linnaeus. Dahlias originated in the mountains of Central America. They were exported from Mexico to Spain in hope of developing a new food plant. The thought was that the tubers might be both edible and palatable. The first two species to enter Europe in the late 1700s were Dahlia coccinea and Dahlia pinnata.

Growth Habit: Compact perennial usually with tuberous root.

Size: With the exception of modern low-growing bedding dahlias, most grow 4 to 6 feet tall, but can be maintained as lower, bushier plants with regular pinching and staking.

Foliage: Pinnate leaves consist of oval mid- to dark green, slightly hairy leaflets.

Exposure: Full sun.

Culture: Grows in humus-rich, well-drained soil. Prefers growth-promoting high-nitrogen liquid fertilizer each week during early summer, followed by bloom-boosting high-potassium (10-30-10, or something similar with middle number higher than other numbers) liquid fertilizer each week from midsummer to early autumn.

Hardiness: Lift for winter if not in zone 8 or warmer. Dahlias may survive our Zone 7 winter if it's mild and the plants have a good layer of mulch to protect their tuberous root system.

Varieties: The American Dahlia Society recognizes 17 flower forms, and the International Register of Dahlias lists more than 20,000 cultivars.