How to Grow Dahlias
Dahlia pinnata
Show-stopping summer-to-frost blooms grown from tender tubers.
By the Plants by Zone Editorial Team · Reviewed June 1, 2026
About dahlias
Dahlias are tender, tuberous perennials that produce some of the most spectacular and varied blooms in the garden, from pompoms to dinner-plate giants. They flower tirelessly from midsummer until frost, especially when cut often. In cold zones the tubers are lifted and stored over winter; in warm zones they can stay in the ground.
When to plant and harvest dahlias
Timing is relative to your frost dates. Find your USDA zone for exact dates, or browse the month-by-month calendars.
Start seeds indoors
Start tubers indoors 4–6 weeks before last frost (cold zones)
Transplant outdoors
After last frost, once soil is warm
Direct sow
Plant tubers outdoors after last frost
Harvest
Midsummer until frost
How to grow dahlias step by step
- 1
Wait for warm soil after the last frost, then plant tubers 4–6 in deep with the eye facing up.
- 2
Stake tall varieties at planting time — their hollow stems snap easily once loaded with blooms.
- 3
Hold off heavy watering until shoots appear, then water deeply and consistently.
- 4
Pinch the growing tip above the third or fourth leaf pair for bushier, more floriferous plants.
- 5
Deadhead and cut blooms often — the more you pick, the more they flower.
- 6
In cold zones, lift, dry, and store tubers after frost blackens the foliage.
Common problems growing dahlias
⚠ Tall plants flop or snap
Stake at planting time; the hollow stems can’t support big blooms unaided.
⚠ Lush leaves but few flowers
Too much nitrogen — feed with a lower-nitrogen, higher-potassium fertilizer once budding starts.
⚠ Earwigs or slugs chewing buds
Trap earwigs in rolled newspaper and use slug controls around emerging shoots.
✗ Keep away from
🧺 Harvesting dahlias
Cut dahlias when blooms are nearly fully open, since they barely open further once cut, choosing the cool of the morning and plunging stems straight into water. Cutting and deadheading often is the secret to nonstop flowers right up to frost.
Dahlias: frequently asked questions
Do I have to dig up dahlia tubers each year?＋
In zones colder than about 8, yes — lift the tubers after frost, dry and store them somewhere cool and frost-free, then replant in spring. In mild zones they can overwinter in the ground with mulch.
How do I get more dahlia flowers?＋
Pinch the growing tip early for a bushier plant, then cut blooms and deadhead constantly — dahlias flower more the more you harvest.
Grow dahlias in your zone
See exactly when to plant and what else to grow alongside dahlias, tailored to your USDA hardiness zone.
