Why Are Dahlias Not Growing This Year?

Climate

• Dahlias revel in warm temperatures and full sun. Dahlias that receive less than six hours of direct sun per day will not grow well nor bloom. Dahlia tubers do not begin growing until spring soil temperatures have reached 60 degrees.

Basic Needs

• Dahlias need fertile, well-drained soil. Growth may be stunted if the soil is heavy clay or waterlogged. Nitrogen-rich fertilizers weaken dahlia stems and inhibit blossoms.

Problems

• As with many plants, dahlias suffer from pests and diseases that stunt growth. Pests such as aphids, spider mites and thrips feed on plant parts. Blight, wilts and powdery mildew weaken the dahlia and shorten its growing season.