Dahlia is a tuberous-rooted perennial flower in the aster family. It begins blooming in midsummer and continues until the first frost. Their showy, distinct flowers come in a range of shapes, sizes and patterns and sit atop the straight, sturdy stems. Dahlia grows in a rainbow of bright colors, except blue, with some bicolored flowers that have more than one color swirled together. The toothed, feathery leaves on dahlia flowers range from mid to dark green. Dahlia flowers grow best in full sun and well-drained soil that is organically rich. They make ideal flowers to grow in groups along borders or tucked into containers. Purchase dahlia plants from a nursery. Look for strong stems and green leaves that indicate a healthy flower.
Select a well-drained area and one that is sheltered from strong winds. Keep the dahlia away from outbuildings or large trees that create too much shade. Remember the best flowering occurs in full sun, but in hot summer climates, a smattering of filtered shade is desirable.
Space 1 to 3 feet apart, depending upon variety, to ensure room for growth and proper air circulation around the flowers.
Add a mixture of half soil and half compost to fill the planting site. With a shovel, mix the soil together, but don’t pack it down. Dahlias need a nutrient-rich soil amended with organic matter, like compost.
Remove the dahlia from the nursery container and remove excess soil and mulch from the plant. You don't need to remove a peat or fiber pot.
Dig a hole for each dahlia that's the same depth as the planting pot and twice as wide.
Place the dahlia into the ground and gradually cover the roots with soil. Gently press down on the soil to ensure the dahlia is securely buried.
Stake tall dahlia plants with a 6-foot stake. Place the stake into the soil next to the roots of the plant. Gently tie stems to the stake with stockings or twine. Ensure at least a ¼ inch of slack for growth.
Water dahlia plants immediately, soaking the soil. Keep dahlias moist during the growing season. Don’t let the soil dry out.
Mulch around the base of the dahlia, leaving a 2- to 3-inch-wide ring around each plant. Use compost, hay or straw to help plants retain water and prevent evaporation.
Fertilize dahlia plants monthly with low-nitrogen fertilizer.