Problems: Aphids often attack developing vines.
Pea weevils can chew on foliage, especially along the edges of young leaves. They are serious only when they attack young seedlings. Apply Beauveria bassiana as soon as damage is spotted to head off problems.
Thrips—very tiny black or dark brown insects—often hide on the undersides of leaves in dry weather. They cause distorted leaves that eventually die; thrips also spread disease. Control them with an insecticidal soap spray.
Crop rotation is one of the best ways to prevent diseases. To avoid persistent problems, don't grow peas in the same spot more than once every 5 years.
Plant resistant cultivars to avoid Fusarium wilt, which turns plants yellow, then brown, and causes them to shrivel and die.
Root-rot fungi cause water-soaked areas or brown lesions to appear on lower stems and roots of pea plants. Cool, wet, poorly drained soil favors development of rots. To avoid root rot, start seeds indoors in peat pots and wait until the soil is frostless before setting out the plants. Provide good fertility and drainage for strong, rapid growth.
Warm weather brings on powdery mildew, which covers a plant with a downy, white fungal coating that sucks nutrients out of the leaves. Bicarbonate sprays can help to prevent mildew. Destroy seriously affected vines, or place them in sealed containers for disposal with household trash. Avoid powdery mildew by planting resistant cultivars.
Control mosaic virus, which yellows and stunts plants, by getting rid of the aphids that spread it.
Harvesting: Pods are ready to pick about 3 weeks after a plant blossoms, but check frequently to avoid harvesting too late. You should harvest the peas daily to catch them at their prime and to encourage vines to keep producing. If allowed to become ripe and hard, peas lose much of their flavor. Also, their taste and texture are much better if you prepare and eat them immediately after harvesting; the sugar in peas turns to starch within a few hours after picking.
Pick shell and snap peas when they are plump and bright green. Snow-pea pods should be almost flat and barely showing their developing seeds. Cut the pods from the vines with scissors; pulling them off can uproot the vine or shock it into nonproduction.
Preserve any surplus as soon as possible by canning or, preferably, by freezing, which retains that fresh-from-the-garden flavor. To freeze peas, just shell and blanch for 1½ minutes, then cool, drain, pack, and freeze. Snow peas, which are frozen whole, are treated the same way, but don't forget to string them first if necessary. Peas have a freezer life of about 1 year.
If peas become overripe, shell them and spread them on a flat surface for 3 weeks or until completely dry. Store in airtight containers and use as you would any dried bean.