When to plant and prune Sweet pea
Lathyrus odoratus
Annual sweet peas stop flowering as soon as seedpods are allowed to develop. Pick or deadhead constantly all summer; missing a week of picking effectively ends the display.
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 | early April to early May | early June to late August | early June to late August |
| South Coast and Channel | early April to early May | early June to late August | early June to late August |
| Greater London (Urban Heat Island) | early April to early May | early June to late August | early June to late August |
| South East and Home Counties | early April to early May | early June to late August | early June to late August |
| East Anglia | early April to early May | early June to late August | early June to late August |
| Midlands and Lowland Wales | early April to early May | early June to late August | early June to late August |
| Wales and West Coast | early April to early May | early June to late August | early June to late August |
| Northern England | early April to early May | early June to late August | early June to late August |
| Scotland Lowlands and Central Belt | early April to early May | early June to late August | early June to late August |
| Scotland Highlands and Islands | early April to early May | early June to late August | early June to late August |
| Northern Ireland | early April to early May | early June to late August | early June to late August |
| Channel Islands and Isle of Man | early April to early May | early June to late August | early June to late August |
How to prune it
Pick flowers or deadhead as often as possible - at least twice a week - and pinch out the tips of spring-sown plants at 7.5-10cm.
Severity: deadhead.
Feeding
High-potassium liquid feed for plants growing in containers through the flowering season.
At a glance
- Type
- Annual
- Hardiness
- H4
- Eventual height
- 2.0 m
- Eventual spread
- 0.3 m
- Years to maturity
- 1
- Spacing
- 20 cm
- Sun
- Full sun
- Soil
- Fertile, moisture-retentive but well-drained soil, ideally enriched with organic matter before planting
- Evergreen
- No
- Fragrance
- Scented
- Pollinator value
- 4 out of 5
- Grows in a container
- Yes, 15 litres or more
- Difficulty
- Medium
Safety
RHS lists Lathyrus (except L. sativus) as having pods and seeds that are not edible - do not let children mistake sweet pea pods for edible peas.
Growing notes
An annual climber that lasts one season only: sow in October-November or from late January to April, plant out in April, and clear the plants at the end of summer. Autumn-sown plants branch naturally, while spring-sown plants should have their tips pinched out at 7.5-10cm. Needs canes, netting or a wigwam from the start - typically 2m of support. Spring sowings flower about 12-14 weeks after sowing.
What usually goes wrong
- powdery mildew
- aphids (and the viruses they spread)
- slugs and snails on young plants
- leggy seedlings in poor light
- flowering stopping if pods are left to form
Related guides
Cross-checked against RHS guidance.