With their variety of colors, shapes, and sizes, dahlias bring life to your landscape from late summer into fall. Here’s how to successfully plant and care for these tender plants. 1. Plant the tubers once all danger of frost has passed. Choose a location with fertile, well-drained soil that gets at least 6 hours of sun a day. The plants like sandy or loamy soil but will do fine in clay if you work in a 2-4-inch layer of well-rotted manure or compost before planting.
Smaller varieties should be spaced 1-3 feet apart, larger ones 2-5 feet apart. 2. For each tuber, dig a hole about 12 inches wide and 8-10 inches deep. Mix a shovelful of compost and a handful of bone meal into the soil you removed, or add a timed-release fertilizer according to package directions. 3. Fill each planting hole with the soil mixture until it is about 4 inches deep. 4. Taller plants may need to be staked. To avoid damage to the roots, drive a stake into the ground now, a few inches from where you plan to plant each bulb or tuber. Stakes can be made of wood or bamboo, or they can be metal fence posts. 5. Place a tuber horizontally in the bottom of each hole with the eye pointing upward and the roots down. Cover with 2 inches of soil. Shoots should emerge from the holes in about 2 weeks. 6. As the taller varieties grow, tie them to their stake with twine.