Yardlong Bean Vigna unguiculata

Cowpea or long bean is a tropical, annual climber in the bean family (Fabaceae). It is native to tropical Africa, but it is cultivated throughout warm areas of the world. The species epithet is Latin for “clawed” and refers to the narrow petal base (“clawed petals”). Long bean is V. unguiculata subsp. sesquipedalis. The subspecific epithet is Latin for “foot and a half” and references the extraordinarily long pods.

As a spring-sown, summer cover crop, cowpea is good at weed suppression, growing rapidly in a wide variety of soil types. It fixes nitrogen and improves soil fertility. Slightly acidic soil, a pH of 5.5 to 6.5, is best, and seeds germinate when the soil is warm. It is intolerant of frost, water-logged soil and flooding. It grows best in full sun.

As a vegetable, long bean is a warm-season crop. The plants are vigorous and need a sturdy trellis on which to climb. It is highly tolerant of heat and humidity. Follow the recommendations for the cover crop culture. Harvest the beans when they are 12 to 14 inches long and about half the diameter of a pencil (i.e., before the seeds fill the pods). The pods should be firm and snap when bent. Harvest daily to keep the vines productive.

Grow long bean as a trellised vegetable in the edible garden, or use cowpea as a summer cover crop.

Click here to see a calendar of planting schedules, time-to-harvest, and recommended spacing.

Insects, Diseases, and Other Plant Problems: In hot, humid weather, cowpea is susceptible to powdery mildew. Some cultivars are resistant to nematodes (and can be used as part of a nematode suppression rotation strategy). In Florida, ‘Mississippi Silver’ and ‘Iron Clay’ were found effective against southern root-knot nematode, but other cultivars were highly susceptible and increased the nematode population. If the crop is allowed to set seeds, volunteer seedlings can be troublesome. Insect pests include aphids and plant hoppers.