How to Grow Dahlia
Bulb
Dahlias are tender tuberous perennials from Mexico and Central America, grown across the US for their long summer-to-fall bloom and huge range of flower forms and colors. Home gardeners love them because a single tuber can produce dozens of showy blooms, from tiny 2-inch pompons to dinner-plate flowers a foot wide. They are one of the best cut flowers a backyard grower can raise.
Planting
Plant dahlia tubers outdoors in spring after all danger of frost has passed and the soil has warmed to about 60 degrees F, usually around your average last-frost date. Choose a spot with full sun (at least 6 to 8 hours) and loose, well-drained soil rich in organic matter; dahlias rot in cold, soggy ground. Dig a hole about 4 to 6 inches deep, lay the tuber on its side with the growing eye pointing up, and cover it, spacing plants 12 to 24 inches apart depending on the variety's mature size. To get a head start in short-season areas, you can pot tubers indoors 4 to 6 weeks before your last frost and transplant them out once the weather settles.
Care
Water sparingly until the shoots emerge, then keep the soil evenly moist with a deep soak of about 1 inch per week, watering at the base to keep foliage dry. Feed with a balanced garden fertilizer that is lower in nitrogen a few weeks after sprouting and again as buds form, following the label on whatever product you choose; too much nitrogen gives leaves at the expense of flowers. Pinch out the growing tip above the third or fourth leaf pair when plants are about a foot tall to encourage bushier growth, and stake tall or large-flowered types early so stems do not snap. Deadhead spent blooms regularly to keep new flowers coming, and in USDA zones 7 and colder, dig and store the tubers in a cool, dry, frost-free spot over winter.
Bloom time
Dahlias bloom from midsummer until the first hard fall frost, giving roughly two to three months of continuous color when deadheaded regularly.
Garden uses
Dahlias are outstanding cut flowers with a long vase life and make bold choices for borders, backgrounds, and large containers. Open-centered single and collarette types also draw bees and other pollinators.
Tips
Cut flowers in the cool morning when blooms are nearly fully open, since dahlias do not continue opening much once cut. Keep the plants deadheaded and well watered through late summer heat for the heaviest fall flush, and label your tubers by color and form at digging time so you know exactly what you are replanting next spring.
General guidance for US gardens. Timing and hardiness vary by region; check your local frost dates and hardiness zone. Page updated Aug 4, 2026.