Cowpea

Cowpea is direct-sown after the danger of frost has passed, once soil temperatures reach a consistent 65 to 70°F, at a depth of about 1 to 2 inches; seed germinates and establishes quickly. It prefers well-drained sandy loam soils with a pH between 5.5 and 6.5, tolerates poor and acidic soils, and grows in full sun. Because its root nodules fix nitrogen, cowpea does not require nitrogen fertilizer, and its deep taproot, sometimes exceeding 8 feet, makes the crop notably drought resistant and able to draw on moisture deep in the soil profile. Vining types need a sturdy trellis when grown as a climbing vegetable, while bush types are more compact and suited to mechanical harvest.

Cowpea can be affected by a range of fungal diseases including anthracnose, ascochyta blight, brown rust, cercospora and pseudocercospora leaf spot, charcoal rot and fusarium wilt, along with bacterial canker, southern stem blight and cowpea mosaic virus; humid weather also favors powdery mildew. Recommended responses include planting certified disease-free or resistant seed and removing crop debris after harvest to reduce sources of infection. Insect pests include aphids, plant hoppers, grasshoppers, curculio weevil, southern cornstalk borer and armyworms, and root-knot nematode can build up in susceptible plantings. If plants are allowed to set seed, volunteer seedlings can become a nuisance in following seasons.

When grown as a fresh vegetable, long-podded types are picked at 12 to 14 inches, about half the diameter of a pencil, before the seeds fill the pod; the pods should be firm and snap cleanly when bent, and vines are harvested daily to keep them productive. Cowpea grown for green shelled peas is picked while the seed is still high in moisture, for use fresh, canned or frozen, whereas dry seed types are left in the field until pods and leaves dry down, typically maturing 90 to 100 days after planting, and can then be combine-harvested.

Culinary: Cowpea seed is eaten fresh as green shelled peas or dried and cooked as beans, and the immature pods are prepared much like snap beans; the tender leaves are also used as a cooked green, particularly in Africa.

Forage: The plant is cut for hay or silage and can be lightly grazed after flowering, with digestibility and yield in some cultivars comparable to alfalfa; it is often ensiled together with sorghum or maize.

Cover crop: Fast growth, nitrogen fixation, weed suppression and a deep taproot make cowpea a widely used summer cover crop and green manure, valued for erosion control and for improving soil fertility ahead of a following crop.

Wildlife: Deer browse the foliage and cowpea is planted in food plots for them, while birds including wild turkey eat the seed and the plant provides cover for quail.

Cowpea is native to tropical Africa, where its cultivation and domestication trace back roughly five to six thousand years and developed alongside the ancient West African cultivation of sorghum and pearl millet. From there it spread into cultivation across the Mediterranean and became a staple protein source in the Old World, with Roman writers such as Pliny referring to it under the name phaseolus. It later moved into the Americas and other tropical and subtropical regions, and Thomas Jefferson is credited with introducing the English name cowpea.