Kidney Bean

Kidney bean is a dried-bean form of the common bean, Phaseolus vulgaris. The plant is an annual, twining climber with three leaflets per leaf, and its pods hold the seeds, which are also called beans. The species reaches 2.5 to 4 metres (about 8 to 13 feet) tall with a spread of 0.5 to 1 metre (about 1.6 to 3.3 feet), and many selected varieties are dwarf.

Sow once the soil has warmed. When soils are above 60 °F (16 °C), plant seeds 1 inch (2.5 cm) deep and 2 to 3 inches (5 to 8 cm) apart in rows 18 to 24 inches (45 to 60 cm) apart. Seedlings usually emerge in 7 to 10 days when the soil is 65 to 85 °F (18 to 29 °C). Timing differs between guides: one says to start about one week before the last frost-free date, while another says to seed after the danger of frost is past. Depth also differs, as one guide says to cover the seed with ¼ to ½ inch (0.6 to 1.3 cm) of soil or compost. Beans are legumes and fix nitrogen from the air, so they need little extra nitrogen.

Watering. Keep the root zone moist by watering deeply and regularly during dry periods. Keep soil evenly moist, since water needs are most critical during flowering and pod sizing. Avoid overwatering, which promotes root rot.

Care. Control weeds with regular cultivation, especially when plants are small. Adding more nitrogen stimulates excessive leaf growth and can delay flowering and reduce pod set. Pole types need a trellis, and most bush varieties don’t need support.

Keep the root zone moist by watering deeply and regularly during dry periods. Hot weather above 95 °F (35 °C) and dry conditions can make flowers drop, so keep the soil moist and use organic mulch during flowering. Organic mulches help conserve water and reduce the need for weeding.

Most beans grow fast and are not susceptible to many production problems. One guide lists bacterial blight, Cercospora leaf spot, Mexican bean beetle, spider mites, and powdery mildew as common bean problems. Another page reports no significant problems for the species.

For dry beans, pods should remain on the plant until they are dry and brown. Dry beans are harvested when the pods are fully mature and beginning to dry. Once plants are dry, remove the pods, shell out the seeds, and let the seeds dry further.

For long-term storage, keep the dried seeds in sealed containers in a cool, dry place.

Raw or undercooked beans, especially kidney beans, cause severe nausea, vomiting, and diarrhea. The toxin named for this is phytohaemagglutinin, a lectin, found in the seeds. Never eat raw or undercooked kidney beans.