How to Grow Sweet Peas
Lathyrus odoratus
When to Start
Direct sow outdoors as soon as soil reaches 5°C — typically early to mid spring. Can also be started indoors 4 weeks earlier for a head start.
Don't know your frost date? Find it here →
Growth Stages
Approximate days from start
Care Essentials
- High-potash liquid feed weekly once flowering starts.
- The more you pick, the more they flower. Soak or nick seeds before sowing. Need a tall support (1.8m+).
Companion Planting
—
Growing Conditions
Get a personalized schedule for Sweet Peas based on your exact frost dates
Start planning freeEnter your last frost date to see your dates
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
Want your full season plan with reminders? Try Leaftide free
Spacing & Planting
| Plant spacing | 15 cm |
| Row spacing | 45 cm |
| Sow depth | 2 cm |
| Mature height | 200 cm |
| Mature spread | 30 cm |
A climbing annual. Space seeds along the base of a support structure (trellis, netting, or teepee). Sowing in a zig-zag pattern gives a denser display.
Care Guide
- Feeding
- High-potash liquid feed weekly once flowering starts.
- Watch for
-
- Aphids
- Powdery mildew
- Pea moth
- Mice (eat seeds)
Pests & Diseases
Pest Aphids
Identification: Clusters of green or black insects on growing tips, tendrils, and flower buds; sticky honeydew; distorted growth; sooty mould
- Blast off with a jet of water
- Spray with insecticidal soap, targeting shoot tips and undersides of leaves
- Encourage ladybirds, lacewings, and hoverflies
- Spray with a systemic insecticide containing acetamiprid; avoid spraying open flowers to protect pollinators
Pest Slugs and Snails
Identification: Seedlings eaten at ground level; ragged holes in young leaves; slime trails on foliage and around pots
- Apply organic slug pellets (ferric phosphate based) around seedlings
- Use copper tape around pots and containers
- Hand-pick at dusk; use beer traps
- Apply ferric phosphate slug pellets around vulnerable plants
Pest Mice
Identification: Seeds disappear from pots or drills; disturbed soil where seeds were sown; seedlings nipped off at ground level
- Cover seed trays and pots with fine mesh or chicken wire until seedlings are established
- Sow in a greenhouse or on a high shelf away from mouse access
- Set humane traps near sowing areas
Disease Powdery Mildew Erysiphe pisi
Symptoms: White, powdery coating on leaves and stems; leaves yellow and die back; flowering declines
Treatment: Remove badly affected leaves; spray with a sulphur-based fungicide or potassium bicarbonate solution
Prevention: Space plants for good airflow; water at the base; avoid overhead watering; keep roots cool with mulch
Disease Foot Rot Fusarium spp.
Symptoms: Dark, water-soaked lesions at the base of stems; plants wilt and collapse; roots may be brown and rotting
Treatment: Remove and destroy affected plants; improve drainage; avoid overwatering
Prevention: Use clean compost for sowing; avoid waterlogged soil; rotate planting positions; do not sow too deeply
Disease Pea Mosaic Virus Pea seed-borne mosaic virus
Symptoms: Mottled, streaked leaves with yellow and green patterns; stunted growth; flowers may show colour-breaking streaks
Treatment: No cure — remove and destroy infected plants to prevent spread
Prevention: Control aphids which spread the virus; remove infected plants promptly; do not save seed from affected plants
Growing Conditions
| Min. soil temperature | 5°C |
| Germination temperature | 12–18°C |
| Base growth temperature | 4°C |
| Min. daylength to start | 9h |
| Photoperiod sensitivity | long day |
Frequently Asked Questions
- How far apart should I plant Sweet Peas?
- Plant Sweet Peas 15cm apart with 45cm between rows.
- When does Sweet Peas flower?
- Sweet Peas typically flowers approximately 70 days after transplanting.
- Is Sweet Peas frost hardy?
- Sweet Peas is classified as Hardy.
Plan Sweet Peas in your garden — get personalized frost-date scheduling
Start planning free