Sweet pea Lathyrus odoratus
Sweet pea (Lathyrus odoratus) is an annual flowering plant in the Fabaceae family. It grows 1.5–2.5 m (4.9–8.2 ft) tall and 30–50 cm (12–20 in) wide, wants full sun and moderate water, and is hardy to about -6 °C (21 °F). Space plants about 15 cm (6 in) apart.
Plan Sweet pea in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Sweet pea at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Fabaceae |
| Mature height | 1.5–2.5 m (4.9–8.2 ft) |
| Mature spread | 30–50 cm (12–20 in) |
| Spacing | 15 cm (6 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance none, waterlogging tolerance none |
| Cold hardiness | About -6 °C (21 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 26 °C (79 °F) |
| Flowering | about 11–16 weeks after planting, for 9–14 weeks |
| Days to maturity | About 100 days from planting |
| Wind tolerance | None |
| Pollinator value | High |
| Edible | Not grown as food |
| Common in gardens of | 🇬🇧 United Kingdom, 🇺🇸 United States, 🇦🇺 Australia |
Is Sweet pea toxic?
- People: moderately toxic
- Cats: moderately toxic
- Dogs: moderately toxic
- Parts: seeds, pods
Seeds contain lathyrogens and are toxic if eaten in quantity.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Sweet pea
Good neighbours
- good With Sweet corn: "Three sisters": climbing beans use corn as a support and fix nitrogen; the benefit to the corn is modest but real in low-input soils. Evidence C
Keep apart or take care
- caution With Alliums (onion family): Onions, garlic and leeks are said to stunt beans and peas (allium root exudates may reduce nodulation). Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
- caution With Alliums (onion family): Beans and peas are traditionally kept away from onions, garlic and leeks. Traditional companion-planting advice; controlled trials are few, so treat it as a soft preference. Evidence D
- caution With Fennel: Fennel is reported to suppress beans and peas growing next to it. Evidence C
Questions about Sweet pea
- How far apart should I plant Sweet pea?
- About 15 cm (6 in) apart, centre to centre. A mature plant spreads 30–50 cm (12–20 in).
- Does Sweet pea need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Sweet pea need?
- Moderate water. Drought tolerance is none and waterlogging tolerance none.
- How cold-hardy is Sweet pea?
- It tolerates about -6 °C (21 °F) once established, roughly USDA zone 9. As an annual it is usually planted out after the last frost.
- When does Sweet pea flower?
- About 11–16 weeks after planting, for 9–14 weeks.
- Is Sweet pea poisonous to cats and dogs?
- For cats it is moderately toxic; for dogs moderately toxic; for people moderately toxic. Seeds contain lathyrogens and are toxic if eaten in quantity.
- What grows well with Sweet pea?
- "Three sisters": climbing beans use corn as a support and fix nitrogen; the benefit to the corn is modest but real in low-input soils.
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- FAO Irrigation and Drainage Paper 56 — Crop Evapotranspiration, FAO
- RHS Plant Finder, Royal Horticultural Society
- University extension gardening guides (general), Various land-grant university extensions
Notes and assumptions
- Typical garden-cultivar values; varieties differ.
- Not the edible garden pea; do not eat any part.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Bush bean Phaseolus vulgaris
- Garden pea Pisum sativum
- Runner bean Phaseolus coccineus
- Broad bean (fava) Vicia faba
- Lima bean Phaseolus lunatus
- Cowpea (black-eyed pea) Vigna unguiculata
- Yardlong bean Vigna unguiculata subsp. sesquipedalis
- Soybean (edamame) Glycine max