Dahlias

Dahlias are flowering plants in the genus Dahlia of the daisy family (Asteraceae). Native to Mexico and Central America, they are prized for large, colorful blooms. They grow from underground tubers and are herbaceous perennials in warm climates; in temperate zones they are often grown as annuals or kept as tubers over winter. Blooms typically appear from midsummer to the first frost.

Cultivars number in the thousands and cover a wide range of flower forms, colors, and sizes. Common shapes include decorative, pompon, ball, cactus, and collarette. Blooms can range from a few centimeters to more than 20 centimeters in diameter, and plant height varies from compact 30-centimeter types to tall specimens over 1.5 meters.

Cultivation requires a sunny site and well-drained soil, with regular moisture and feed. Support is often needed for tall varieties. Plant after frost danger in spring and space according to mature size. Deadhead faded flowers to extend blooming, and cut back in mid- to late season if growth slows. In cold regions, lift and dry tubers in autumn and store them frost-free.

Propagation is mainly by division of established tubers or by cuttings; seed is used primarily to create new varieties and does not breed true to parent traits. Common pests include aphids, slugs, and spider mites; diseases include powdery mildew and botrytis. Good air circulation helps prevent problems.

Dahlias are popular ornamental plants for borders, beds, and containers, and their long stems and range of colors make them favored cut flowers for arrangements.