Dig a hole 8 to 10 inches deep and wide enough to accommodate the tubers. Loosen the soil in the bottom of the hole and refill to a depth of 6 inches. Set the tuberous root on its side, with the eyes facing upward. Cover with 2 to 3 inches of soil. Soil should be filled in around the plants as they develop until the surface is level.
Many gardeners insert a stake at the side of each hole at planting for future support.
Each tuberous root usually produces multiple shoots. While you can leave all the shoots to grow, thinning will produce flowers of higher quality. Leave one to four of the strongest shoots. When plants are about a foot tall and display 3 to 4 pairs of leaves, pinch out the terminal shoot to encourage branching. Tall-growing dahlias should be staked to support the long stems and large flowers.