How to grow Dahlia
Updated October 2026
Dahlias are tuberous perennials from Mexico and Central America, grown for big, showy flowers in almost every color and form, from small pompons to dinner plate blooms. Planted after frost, they flower from summer until the first frost and make superb cut flowers. In cold regions the tubers are dug and stored over winter; where winters are mild they can stay in the ground under mulch.
📖 Our full guide: How to Grow Dahlia
Where to plant
Dahlias need fertile, moist but well drained soil and full sun to part shade. Despite their tropical origins they can languish in summer heat, so in hot regions give them afternoon shade, mulch and plenty of water; they then flower strongly from late summer to frost.
Plant tubers after the last frost once the soil is warm. In Florida, the Gulf South, Texas and the desert, plant in early spring and again in late summer for fall flowers. In California, plant from March to July. Across the North, the Midwest, the Mountain West, the Pacific Northwest and Alaska, plant in May or June.
Choosing a variety
The American Dahlia Society recognizes 29 flower groups, including single, anemone, collarette, waterlily, decorative, pompon, cactus and semi cactus. Dinnerplate types give huge blooms for cutting but need staking; low bedding dahlias suit pots and borders. Dahlias grown from seed are usually dwarf and less reliable than named tubers.
How to plant
- Dig the bed deeply and work in compost.
- For tall varieties, put the stake in the hole before planting so you do not spear the tuber later.
- Lay each tuber on its side with the eye (growing point) facing up, and cover with about 3 inches (8 cm) of soil.
- Water lightly once at planting, then wait until shoots appear before watering regularly; wet, cold soil rots tubers.
- Space tall types about 2 feet (60 cm) apart, closer for small ones.
Watering and feeding
Once growing, water deeply and regularly, especially in hot weather, and mulch to keep the roots cool and moist.
Feed lightly with a balanced or low nitrogen fertilizer during the season. Too much nitrogen gives lush leaves and weak stems with fewer flowers.
Pruning and care through the year
- Tie tall varieties to their stakes as they grow.
- Pinch out the main tip when plants are about a foot tall for bushier plants with more flowers.
- Deadhead spent flowers to extend the bloom season.
- In zones below 7, dig the tubers after frost blackens the tops. Dry them carefully without washing and store in vermiculite or dry sand at 35 to 45°F (2 to 7°C). In zones 7 to 10, cut back the tops and mulch over the tubers instead.
Cutting flowers
Cut dahlias in the cool of the morning when the flowers are almost fully open, as buds do not open well once cut. Put the stems straight into water. Regular cutting encourages more flowers.
Growing in pots
Compact and bedding dahlias grow well in a pot at least 12 inches (30 cm) wide with a rich, free draining mix. Water often in summer and move the pot to a frost free place in winter.
Propagation and saving seed
Divide clumps in spring before planting, making sure each piece has part of the old stem with an eye, as tubers without an eye will not grow. Dahlias can also be grown from cuttings of new shoots.
Companion planting
Dahlias pair well with other summer flowers in a cutting garden or pollinator border.
Good companions
Pests and diseases
Slugs and earwigs damage young shoots and flowers; most diseases come from wet soil or crowding.
Pests to watch for
- Slugs and snails Young shoots grazed to the ground in damp weather.
- Earwigs Ragged holes in petals and leaves, with the insects hiding in flowers by day.
- Aphids Clusters on buds and shoot tips; they spread viruses.
Diseases to watch for
- Powdery mildew White powdery coating on leaves in late summer.
- Botrytis Gray mold on flowers and buds in wet weather.
- Dahlia mosaic virus Mottled, distorted leaves and stunted plants. Discard affected plants and tubers.
- Root rot Tubers that rot in cold, wet soil, and plants that wilt and collapse.
Common questions
Do I need to dig up dahlia tubers in winter?
In zones below 7, yes: dig after frost, dry without washing and store in vermiculite or dry sand at 35 to 45°F. In zones 7 to 10, mulch over them and leave them in the ground.
How deep should I plant dahlia tubers?
Lay them on their side with the eye up and cover with about 3 inches of soil.
Why are my dahlias not flowering?
Usually too much shade, too much nitrogen, or summer heat. Give them sun (with afternoon shade in hot areas), feed lightly and keep them watered; they often bloom strongly from late summer.
When should I plant dahlias?
After the last frost once the soil is warm. In Florida and the Gulf South, plant in early spring and again in late summer.
Are dahlias poisonous to pets?
NC State lists dahlias as a problem for cats, dogs and horses, and they can cause skin irritation in some people.
Sources we checked: NC State Extension Gardener Plant Toolbox: Dahlia.
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