Deadheading -- removing faded flowers -- your dahlias (Dahlia group) encourages the plants to produce more blooms. You can also disbud dahlias, which means to remove the flower buds, to promote healthy growth and encourage the remaining flowers to grow large. Dahlias are hardy in U.S. Department of Agriculture plant hardiness zones 7 through 10, and grow 1 to 6 feet tall and 1 to 3 feet wide, depending on the variety.
When to Deadhead
The best time to deadhead dahlias is immediately after the blooms fade. As dahlia flowers age, the petals wilt and change color. Eventually, the petals wither and drop, and seed heads often appear. After plants produce seeds they can stop producing new flowers. Deadheading dahlias as soon as the outer petals wilt stops the seed heads from growing, and prevents the plants from looking unsightly. Dahlias flower summer through fall, and deadheading often should begin in late summer.
How to Deadhead
When deadheading dahlias, it's important to remove the whole flower head and not just the petals. If you only remove the petals, you can leave behind the developing seeds. Dahlias produce flowers at their stem ends.
Hold a dahlia flower at its base where it joins the stem.
Pinch off the flower at the end of the stem.
Remove other faded dahlia flowers in the same way.
Check dahlia plants for fading flowers once or twice per week.
How to Disbud
Remove either the terminal flower buds and side buds or only the side buds on dahlias, depending on the growth stage of the plants. The terminal bud is the flower bud that appears at the end of the stem, and the side buds appear on either side of terminal bud or farther down the stem.
Remove the first terminal bud and side buds that appear on dahlias, usually when the plants are about 15 inches tall. This encourages strong growth that provides plentiful flowers later in the season.
When flower buds appear again and grow to 1/4-inch wide, remove the side buds on both sides of the terminal bud to encourage the remaining bud to grow large.