When to plant and prune Zinnia
Zinnia flowers from early July to late September and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Zinnia is frost-tender, so its timings shift across the UK. Plot works them out from the Midlands and Lowland Wales baseline using Met Office average frost dates.
| Where you are | Plant | In flower | Prune |
|---|---|---|---|
| South West Coast and Cornwall | late April to mid May | early July to late September | early July to late September |
| South Coast and Channel | early May to late May | early July to late September | early July to late September |
| Greater London (Urban Heat Island) | late April to mid May | early July to late September | early July to late September |
| South East and Home Counties | mid May to early June | early July to late September | early July to late September |
| East Anglia | late May to mid June | early July to late September | early July to late September |
| Midlands and Lowland Wales | late May to mid June | early July to late September | early July to late September |
| Wales and West Coast | mid May to early June | early July to late September | early July to late September |
| Northern England | early June to late June | early July to late September | early July to late September |
| Scotland Lowlands and Central Belt | mid June to early July | early July to late September | early July to late September |
| Scotland Highlands and Islands | early July to late July | early July to late September | early July to late September |
| Northern Ireland | late May to mid June | early July to late September | early July to late September |
| Channel Islands and Isle of Man | mid April to early May | early July to late September | early July to late September |
Growing notes
Half-hardy annual, single season only: sow indoors late April to early May, plant out after the last frost, and clear at the end of the season. Flowers from about 12 weeks after sowing, peaking in August and September. Cultivars range from 20-25cm dwarfs to over 1m; space plants 30-40cm apart. Single and semi-double forms are much better for pollinators than the tight fully double types.
At a glance
- Spacing
- 35 cm between plants
- Eventual height
- 60 cm
- Eventual spread
- 30 cm
- Hardiness
- H3
- Sun
- Full
- Frost tender
- Yes
- Grows in a container
- Yes, 10 litres or more
- Balcony rating
- 4 out of 5
Feeding
Potassium-rich liquid feed for container-grown plants during flowering.
Pruning: what to avoid
Zinnias will not tolerate cold: never autumn-sow them, and do not plant out until the frost risk has passed (late May or early June in the south, mid-June in the north). Growth checked by cold rarely recovers.
Pruning group
Pinch out tips at 20-30cm, then deadhead or cut flowers regularly to keep new buds coming
What usually goes wrong
- damping off of seedlings
- grey mould (botrytis) in wet weather
- alternaria leaf blight
- slugs and snails
- growth checked by cold, wet planting-out conditions
Related guides
Timings cross-checked against RHS guidance for zinnia.