Sweet pea

How to recognise it

Habit

Annual climber 1.5–2 m tall (dwarf varieties 30–60 cm), which holds on with tendrils.

Stem

Winged and, like the leaves, softly hairy.

Leaf

One pair of oval leaflets 3–6 cm long with a branched tendril between them.

Flower

Pea flowers 2.5–5 cm across, a few per stem, in white, pink, red, salmon, purple or two colours; strongly scented; from June to September.

Fruit

Hairy pod 5–7 cm long with a few round, greyish-brown seeds.

Confusion with

Garden pea has leaves with several pairs of leaflets, large stipules and hairless pods. Broad-leaved everlasting-pea is a perennial without scent, with hairless stems.

Flowering: June–September · Pruning: April and June–September

Why grow it?

• One of the most fragrant flowers in the garden and an ideal cut flower: every picking brings new buds.
• Flowers for three months, from June to September, if you pick regularly.
• Quick results: in one season a green screen or a flowering fence 1.5–2 m high.
• Old, simple varieties have the strongest scent and attract bumblebees.
• Fixes nitrogen: after the crop it leaves richer soil in the vegetable plot.
• A plant with a long history, from a Sicilian monk to the first experiments in genetics.

Sweet pea: where does it grow best?

• Wild in southern Italy and Sicily, in sunny scrub; here only in gardens.
• Full sun, ideally with a cool root run.
• Deep, humus-rich, moisture-retentive soil, rich in compost and not acid.
• A spot with a trellis, netting, twigs or a wigwam of bamboo canes to climb.

Goes well with

• Pot marigold: An easy annual for the base, also good for cutting.
• Runner bean: Climbs alongside in the vegetable plot and also attracts bumblebees.
• Cosmos: A cut flower that blooms at the same time, in pink and white.
• Nasturtium: A low, colourful plant for the base in the vegetable plot.

Sweet pea: when and how to plant it?

1. Buy seed from a garden centre or nursery, or swap with other gardeners. Never take plants from the wild.
2. Soak the seeds overnight in lukewarm water, or lightly nick hard, dark seeds on one side.
3. Sow in October–November in deep pots in a cold frame or unheated greenhouse, or indoors in February–March; sowing direct outdoors is possible in April.
4. Pinch out the tip above the third or fourth pair of leaves as soon as the seedlings are 10 cm tall: they will branch better.
5. Plant out in April, 20–25 cm apart, at the foot of a support at least 1.8 m tall.
6. Water straight away and keep the soil moist from then on.

Care

Watering

Regularly and generously, especially in dry summers: drought stops flowering and makes it prone to powdery mildew.

Feeding

Compost at planting; during flowering, an organic liquid feed for flowering plants every two weeks.

Picking

Pick every few days: as soon as pods form, the plant stops flowering.

Tying in

Guide young stems to the support and tie them in loosely until the tendrils take hold.

Mulching

A layer of compost or grass clippings at the base keeps the roots cool and moist.

Tip: Pick a bunch every two or three days: as long as the plant is not making pods, it keeps flowering into September.

Pruning and mowing

Pruning months: April and June–September.

When: Pinch out in April; remove faded flowers from June to September.

How:

• Pinch out young plants above the third or fourth pair of leaves for more stems.
• Every few days, pick flowers or cut off faded ones before pods form.
• Clear the plants after flowering; you can leave the roots with their nodules in the soil.

Caution: If you let pods ripen for seed, flowering stops on those stems.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In August, let a few pods from the best plants ripen until brown and dry, and store the seed dry for next year. Sweet peas largely pollinate themselves, so your own seed usually comes fairly true.

Sweet pea: how does it get through the winter?

Hardy to −5 °C: protect in harsh winters.

• Annual: after flowering the plant dies and you clear it away.
• Autumn-sown seedlings overwinter in a cold frame or unheated greenhouse; they tolerate light frost to about −5 °C.
• Store your seed dry, cool and out of reach of mice.

Diseases and pests

• Slugs and snails: They eat seedlings and young shoots. Plant out sturdy, pot-grown plants and collect slugs in the evening.
• Mice: They dig seeds out of the pots. Sow indoors or cover the pots with mesh.
• Powdery mildew: White powder on the leaves in late summer, especially in dry weather. Water, give space and cut off affected leaves.
• Aphids: On tips and buds. Ladybirds help; otherwise spray them off with water.
• Bud drop: Buds fall in cold, drought or big swings in temperature. Water and be patient: it usually passes by itself.

Through the year

• February: Sow indoors in deep pots.
• March: Sow. Harden off autumn-sown seedlings.
• April: Pinch out. Plant out against a support. Sow direct.
• May: Tie in. Watch for slugs.
• June: Flowering begins. Pick.
• July: Full flower. Pick every few days and water.
• August: Flowering. Let a few pods ripen for seed.
• September: Last flowers. Collect seed.
• October: Sow in pots in a cold frame.
• November: Sow in a cold frame.

Did you know?

• In 1699 the Sicilian monk Franciscus Cupani sent seeds of the wild sweet pea to England. The old variety ‘Cupani’ still looks very much like that wild form.
• Around 1900 a sweet pea with a wavy standard petal was found in the gardens of Althorp in England; it gave rise to the large Spencer varieties.
• Around 1905 the British geneticists Bateson and Punnett discovered, using sweet peas, that some inherited traits are passed on together.