How to grow Sweet pea

Lathyrus odoratus

A fragrant annual climber with tendrils, up to about 2 m tall on supports, grown for its pea-like flowers and for cutting. It likes cool weather and struggles in hot, humid summers. The plant is poisonous — do not grow it next to edible peas; it is also toxic to horses.

Quick facts

Type	Flower
Family	Fabaceae
Light	Full sun
Soil pH	6–7
Frost	tolerates light frost
Soil for sowing	from 5 °C
Germination	14 days
Seedlings ready	28 days
Where it grows	Greenhouse, Open ground

When to plant

Sow for seedlings about 6 weeks before planting out.

It tolerates light frost: plant out in open ground about three weeks before your last spring frost.

In an unheated greenhouse everything moves about three weeks earlier.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	—	—
Growth	every 4 days	—	balanced (NPK), at the start of the stage
Flowering	every 4 days	—	balanced (NPK), at the start of the stage

Open ground

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	—	—
Growth	every 4 days	—	balanced (NPK), at the start of the stage
Flowering	every 4 days	—	balanced (NPK), at the start of the stage

Growing notes

Light

Full sun; light dappled shade is tolerated.

Soil

Rich, fertile, well-drained soil with organic matter dug in, pH 6–7; mulch to keep it evenly moist.

Care

Sow in deep pots in autumn (overwinter the seedlings in a cold frame) or from late winter to spring, 1 cm deep at about 15 °C. The hard seed coat germinates better if the seeds are first swollen on moist tissue; seeds soaked overnight must be sown at once or they rot. Pinch out the tips at 7.5–10 cm, harden the plants off for 10–14 days and plant them out in spring next to a support — the seedlings take light frost. In dry weather check them every 3–4 days and water to the full root depth. Feed at planting and again as flowering starts; in containers use a high-potassium feed. Pick or deadhead the flowers often, because once seed pods form flowering stops. Do not grow sweet peas in the same spot two years running. Watch for slugs, snails and aphids.

Sources

Figures checked against these sources.