Dahlias are worth the effort

Dahlias are one of the most spectacular flowers that can be grown in the garden. They have a reputation for requiring lots of care, and if you want to grow show-stopping award winners, that is certainly true. But many types grow easily with minimal care in most gardens.

If you have a sunny spot with reasonably well-drained soil with a pH around 6.5, you can grow dahlias without too much fuss.

If your soil is poorly drained clay, try growing them in raised beds, as you would your vegetables.

Dahlias are a popular addition to the landscape because they have a wide height range (1 to 6 feet) and a variety of flower shapes and sizes (2 to 12 inches). Color range includes orange, pink, purple, red, scarlet, yellow, blue and white. Some flowers are striped or tipped with a different color. Dahlias begin blooming in early summer and continue to frost.

Dahlias can be started from dormant tuberous roots, grown from seeds, rooted from cuttings, or purchased as transplants. To ensure cultivar consistency, buy tuberous roots of named cultivars and save the tuberous roots from year to year. For information on specific cultivars visit the American Dahlia Society Web site: www.dahlia.org.

Dahlias are classified according to flower shape and arrangement of petals. Types of single-flowering dahlias include singles, orchid-flowering, anemone and collaretts. Double-flowering types have multiple rows of petals, grow taller, and have large flowers. Cactus dahlias and semi-cactus types are popular. There are two types of decorative dahlias: formal and semiformal. Ball dahlias and pompons fill out the other main types. Pompons are smaller version of ball dahlias.

Select a sunny (minimum of 6 hours) location protected from strong winds as your planting site. Dahlias grow best in a deep, fertile soil. They are not tolerant of water-logged ground. Incorporate 2 to 4 inches of organic matter such as compost, bark, or well-aged manure and 2 to 4 pounds of 5-5-5 general-purpose fertilizer per 100 square feet (2 to 4 tablespoons per square foot) before planting.

Dahlias are very sensitive to freezing temperatures. Large tuberous roots may be planted about 2 weeks before the last spring frost date. Small tuberous roots and transplants should not be planted until all danger from frost has passed. Spacing between plants depends upon the size of the variety you have chosen. Large-flowering dahlias should be spaced 3 to 4 feet apart; smaller dahlias can be spaced 2 feet apart, down to 9-12 inches for the bedding types grown from seed.

Through the summer, apply a 3- to 4-inch layer of mulch, using compost, bark or other organic material. Dahlias are heavy users of water; keep the soil moist but not saturated. Try to keep the foliage dry unless you are cleaning the leaves of dust. Then, wet them early in the day. Each tuberous root usually produces multiple shoots. While you can leave all the shoots to grow, thinning will produce flowers of higher quality. Leave two to four of the strongest shoots. Tall varieties need to be trained to a stake starting when they are about a foot tall. The larger the flower, the more you will need to stake.

Flower size can be increased by removing lateral flower buds. This is referred to as disbudding. When the three buds that form at the end of each branch reach the size of small peas, remove the two side buds. Small-flowering types should not be disbudded. Faded flowers should be removed to encourage continuous blooming.

Many gardeners are discouraged from growing dahlias because of the need to lift and store them over winter. If you grow them in raised beds, it is possible to overwinter them in place, especially if you cover the soil with plastic to shed the winter rains that may rot the tubers. Since you will need to dig and divide the tubers so they don't get overcrowded, why not just perform that task in the fall and you will be ready to store them for the winter. Dahlias are definitely worth the extra effort needed to grow them and they will reward you many times over for your efforts.

Stan Mapolski, aka The Rogue Gardener, can be heard from 9-10 a.m. Saturday mornings on KMED 1440 AM and seen in periodic gardening segments for KTVL Channel 10 News. Reach him at stanpolski@gmail.com.

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