Dahlias grow 1 to 5 feet tall from tubers, which are a fleshy root. The blooms of dahlia display in late summer and may be daisy-like petals surrounding a mounded center or a mass of petals creating a sphere 2 to 6 inches across. Blooms may be a single color or bi-colors of white, pink, yellow, mauve, deep red or peach. Dahlia tubers will be available at garden centers in late winter for early spring planting. For an eye-catching garden display, choose dahlias in a variety of heights and colors.
Choose a sunny or partially sunny location where the soil drains well.
Dig a hole about 6 inches deep and twice as wide as the tuber. Place the tuber in the ground with the eye up. The eye of the dahlia tuber looks like a small head on a narrow neck-like protrusion from the tuber. If planting in clay soil, dig down 10 inches. Mix 50 percent organic matter, like leaf mold or compost, into the additional 4 inches of soil removed from the hole. Partially refill the hole with the soil/organic mixture to a 6-inch depth, and then put the tuber into the hole.
Cover the tuber with soil that does not contain organic matter. Organic matter on top of the tuber can affect the tuber's growth. Do not water. When planting multiple tubers, space the tubers in the ground about 2 feet apart.
Water when the first sprouts appear, which will be about 4 weeks later. After the sprouts appear, water every 7 to 10 days when there is no rainfall.
Tie taller varieties to a stake. Dahlias that can reach heights over 3 feet need help to stand upright. In about 1 foot intervals, loosely tie the plant to a stake. Make the first tie on the main stalk. As the plant grows, add more ties around the branches.