When to plant and prune Dahlia
Dahlia hybrids
Pinch out growing tips when young; deadhead spent flowers through summer.
Planting, flowering and pruning by region
Pruning is driven by dormancy rather than frost, so it is not shifted by region — the same cut is right in Inverness and in Penzance. Planting windows do move.
| Where you are | Plant | In flower | Prune |
|---|---|---|---|
| South West Coast and Cornwall | mid April to early May | early July to late October | early July to late September |
| South Coast and Channel | late April to mid May | early July to late October | early July to late September |
| Greater London (Urban Heat Island) | mid April to early May | early July to late October | early July to late September |
| South East and Home Counties | early May to late May | early July to late October | early July to late September |
| East Anglia | mid May to early June | early July to late October | early July to late September |
| Midlands and Lowland Wales | late May to mid June | early July to late October | early July to late September |
| Wales and West Coast | early May to late May | early July to late October | early July to late September |
| Northern England | late May to mid June | early July to late October | early July to late September |
| Scotland Lowlands and Central Belt | early June to late June | early July to late October | early July to late September |
| Scotland Highlands and Islands | late June to mid July | early July to late October | early July to late September |
| Northern Ireland | mid May to early June | early July to late October | early July to late September |
| Channel Islands and Isle of Man | mid April to early May | early July to late October | early July to late September |
How to prune it
Pinch out growing tips when young; deadhead spent flowers through summer.
Severity: deadhead.
Feeding
Potassium-rich liquid feed fortnightly from early July to early September, especially for container-grown plants.
At a glance
- Type
- Tender perennial
- Hardiness
- H3
- Eventual height
- 1.2 m
- Eventual spread
- 0.6 m
- Years to maturity
- 1
- Spacing
- 60 cm
- Sun
- Full sun
- Soil
- Fertile, moist but free-draining soil
- Evergreen
- No
- Pollinator value
- 3 out of 5
- Grows in a container
- Yes, 20 litres or more
- Difficulty
- Medium
Winter protection
Lift tubers after first frost blackens the foliage (or by late November at the latest) and store in a frost-free, dry place over winter; in mild areas/light soil, tubers can be left in the ground under a thick mulch.
Growing notes
Plant out only after the last frost (typically late May, early June in colder regions) — dahlias are killed by frost. Staking early prevents wind snap later in the season.
What usually goes wrong
- slugs and snails
- earwigs (flower damage)
- blackfly/aphids
- powdery mildew
- tuber rot in storage
Related guides
Cross-checked against RHS guidance.