Cowpea as a Cover Crop
Legume cover crop
Cowpea (Vigna unguiculata), also called southern pea or field pea, is a warm-season annual legume grown widely as a summer cover crop in gardens and on small farms. It is prized for thriving in heat and on lower-fertility, sandy soils where other cover crops may struggle. Gardeners often use it to keep a bed productive during the hot months between spring and fall plantings.
Benefits
As a legume, cowpea works with soil bacteria to fix nitrogen from the air, which can help supply nitrogen to the crops that follow. Its quick, sprawling canopy shades the ground to suppress summer weeds and reduce soil temperature and surface crusting. The vining growth and fibrous roots help hold soil in place and reduce erosion during summer rains. When the residue is returned to the soil, it adds organic matter and can support soil biology and structure.
When to plant
Cowpea is planted in late spring through summer once the soil has warmed and the danger of frost has passed, since it is sensitive to cold. It is commonly sown as a full-season summer cover or fit into a short window between a spring crop and a fall crop. Seed can be broadcast and lightly raked in or drilled in shallow rows at a general rate suited to your soil and goals; your local Cooperative Extension can suggest a seeding range for your area.
Growing it
Cowpea germinates quickly in warm soil and grows fast, producing trailing or semi-upright vines depending on the variety. It is fairly drought tolerant once established and generally needs little attention through the summer, though even moisture supports better growth. For reliable nitrogen fixation on ground that has not grown cowpea or related legumes before, seed is often paired with the appropriate rhizobia inoculant at planting.
Ending the cover crop
Because cowpea is frost sensitive, a hard freeze will naturally kill the stand where cold winters occur. During the growing season it can be ended by mowing or cutting, and the residue left on the surface as a mulch or turned into the soil with a spade, tiller, or shallow tillage. Terminating before the plants set mature seed helps prevent unwanted volunteers in the next crop and keeps the residue easier to manage.
Best for
Cowpea suits gardeners and small-scale growers in warm regions who want a fast, heat-loving summer cover on sandy or lower-fertility soil. It is a good fit for filling a bed between spring and fall crops or for adding nitrogen and organic matter during the hottest part of the season.
General guidance for US growers. Seeding rates and regional mixes vary; your local Cooperative Extension office and NRCS can help you plan. Page updated Aug 4, 2026.