Pea

Pisum sativum

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At a Glance

The garden pea is one of the widely grown vegetable crops in British allotments and kitchen gardens, valued for its sweet, freshly picked pods and its ability to fix nitrogen into the soil. A cool-season annual, it suits the relatively mild, damp conditions of the UK better than many other legumes and can be sown successionally from late winter through to early summer for harvests stretching from May to October. Peas reward prompt picking: sugars in the pods begin converting to starch within hours of harvest, which is why home-grown peas taste noticeably sweeter than anything that has spent a day in transit.

Overview

Pisum sativum is a member of the Fabaceae (legume) family and behaves as a hardy annual in UK cultivation. It is grown primarily for its immature seeds, which are eaten fresh, frozen, or dried, although some cultivars are produced for edible pods (mangetout and snap peas). Peas climb by means of leaf tendrils and require some form of support for most cultivars, the height of which ranges from about 45 cm in dwarf varieties to over 2 m in tall heritage types.

The crop fits well into rotation plans. Because the plants carry root-nodule bacteria (Rhizobium leguminosarum bv. viciae) capable of fixing atmospheric nitrogen, a pea crop typically leaves the soil in better condition for the leafy crop that follows it. Historically a staple of British agriculture long before the potato arrived from the Americas, the pea remains a fixture of the cottage garden and the modern allotment alike.

Appearance

The pea plant is a climbing or trailing annual with hollow, slightly angular stems and pale grey-green foliage. Leaves are pinnate, usually bearing two or three pairs of oval leaflets and ending in a branched tendril that grips any suitable support. In most cultivars the plant is self-supporting once given pea sticks, netting, or canes to climb on.

Flowers appear in the leaf axils, usually in pairs, and are typical of the pea family in shape, with a large standard petal, two wing petals, and a fused keel. They range in colour from pure white through pale pink to deep purple-blue, depending on the cultivar. Wild Pisum sativum has purple flowers; the white-flowered forms are a derived trait selected in cultivation.

Pods develop from the fertilised flowers and contain four to ten seeds, which is the part generally harvested. The seeds themselves are smooth or wrinkled; wrinkled ("wrinkled-seeded" or "marrowfat") peas are generally sweeter and are the type grown for fresh eating, while smooth-seeded types are typically used for drying, packet peas, or processing. Mature seeds are pale green to yellow when ripe, drying to a buff or brown colour.

Growing Conditions

Peas are cool-season plants and tolerate light frost, which makes early sowing practical in most UK regions. They grow best where daytime temperatures sit between 13 °C and 18 °C; hot, dry weather at flowering reduces pod set and encourages powdery mildew. A sunny, open site is ideal, although peas will tolerate a little light shade, particularly in southern England.

Soil should be free-draining but moisture-retentive, with a pH of around 6.0 to 7.5. Very acidic ground should be limed several weeks before sowing, as the Rhizobium bacteria that fix nitrogen in the root nodules do not thrive below about pH 5.5. Peas are not fussy feeders and generally do not require nitrogen fertiliser; in fact, excess nitrogen encourages leafy growth at the expense of pods. A modest dressing of well-rotted manure or compost worked into the bed the previous autumn is usually sufficient.

Watering is most critical during flowering and pod swelling. A lack of moisture at this stage causes pods to abort or fill poorly, so a thorough soak once or twice a week in dry spells is far more effective than frequent light sprinklings. Mulching with straw or grass clippings helps conserve soil moisture and keeps the roots cool.

Planting and Care

Sowing can begin as soon as the soil is workable in late February or early March in the south of England, and from late March further north. A second sowing in April and a third in late May or early June extends the harvest; sowing later than mid-June is rarely worthwhile because plants struggle in the heat of high summer. Seeds are sown 3 to 5 cm deep, about 5 to 7 cm apart in a flat-bottomed drill 15 cm wide, or in double rows 15 cm apart, with at least 60 cm between double rows to allow access for picking.

Support should be put in place before or at sowing. Twiggy pea sticks, plastic or jute netting stretched between posts, or a row of canes tied with twine all work well. Dwarf cultivars under about 60 cm generally need only short pea sticks and are a sensible choice for exposed sites.

Watering should be steady rather than lavish until flowering begins, after which a more generous supply is needed. A liquid feed is not normally required, but on poor soils a single high-potash feed (such as a tomato fertiliser) at the start of flowering can improve pod set.

Pruning in the strict sense is unnecessary, but pinching out the growing tips of taller plants once the top of the support is reached directs energy into the remaining pods. The tender shoot tips can be eaten as a salad green.

Propagation is by seed only. Saving seed is straightforward: leave a few pods on the strongest plants to mature fully and dry on the vine, then shell and store in a cool, dry place. Because peas are largely self-pollinating, saved seed usually comes true to type, though crossing between adjacent cultivars is possible at low levels.

Seasonal care centres on a few recurring tasks. In spring, watch for mice and pigeons, both of which can decimate a newly sown row; netting or fleece helps. In summer, keep the ground damp, mulch, and pick pods every two or three days to keep plants productive. After the final harvest, cut the tops off at ground level rather than pulling the roots, leaving the nitrogen-rich nodules in the soil to benefit the next crop. The cut foliage makes good compost.

Common Problems

Pea moth (Cydia nigricana) is the most damaging pest in many UK gardens. The small caterpillars feed inside developing pods, making the peas unappetising. The principal defence is to sow early or late enough that the crop is not in flower during the moth's main egg-laying window in June and July; covering flowering plants with fine insect mesh is also effective.

Powdery mildew appears as a white, dusty coating on leaves in warm, dry weather and is worst on late-sown crops. Resistant cultivars are available, and good air circulation, steady watering, and the avoidance of drought stress all reduce infection.

Birds, especially pigeons, will strip young seedlings; black cotton threads stretched above the row, or fleece, deter them. Mice can take sown seed, particularly in gardens with long grass nearby; sowing slightly deeper or using trap crops of pre-germinated seed can help.

Root rot and damping-off can affect seedlings in cold, wet soils. Waiting until soil temperatures are reliably above about 7 °C, and avoiding waterlogged ground, reduces losses.

Downy mildew and leaf and pod spot are fungal diseases that can build up in long, cool, damp springs. Crop rotation, removal of infected debris, and the use of clean seed are the main practical controls for the home gardener.

Popular Varieties

'Feltham First' is a traditional dwarf cultivar reaching about 60 cm, prized for its reliability and very early cropping. It is widely offered by UK seed merchants and is a common choice for the first spring sowing.

'Hurst Green Shaft' is a maincrop wrinkled pea of about 75–90 cm, well known for its long, well-filled pods and is widely listed by UK seed merchants.

'Alderman' is a tall heritage cultivar that can reach 1.8–2.1 m and produces heavy crops over a long season. It needs tall, sturdy support but is a reliable choice for allotments where vertical space is available.

'Kelvedon Wonder' is a compact, early-to-maincrop wrinkled pea that performs well in drier conditions and is frequently listed in UK catalogues. It is particularly valued for heavy crops on poorer soils.

Mangetout and snap types such as 'Oregon Sugar Pod' and 'Sugar Snap' are widely grown for their edible, stringless pods and are useful for later sowings that would not crop well as shelling peas.

Cultivars and Varieties

Pests and Diseases

For step-by-step help, read Controlling Aphids Naturally, Dealing with Slugs and Snails and Treating Powdery Mildew. Or browse the full plant problem solver to diagnose an issue by symptom.

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