Jack Bean is native to the West Indies and Central America. It closely resembles Sword Bean, Canavalia gladiata, and the predominantly African wild species, Canavalia virosa. Jack Bean now is widely distributed in the tropics and subtropics although it is regarded as a minor vegetable rather than a major crop species.
Jack Bean is succeeding as a green manure/cover crop plant because its deep root system can find water during drought and its nitrogen fixation capabilities improve soil nutrients. Jack Bean can be interplanted with cacao, citrus, coconut, pineapple and tobacco. It can also be used as supplementary food for ruminant (cud-chewing) animals, especially if the plant material is dried before it is fed. Jack Bean forage should be introduced gradually as a small percentage of the total diet because of toxins in all plant material. Asians eat the young green pods and seeds but only after thorough cooking. There is some evidence from Colombia that a quantity of fresh Jack Bean leaves placed three nights consecutively on leaf-cutting ant colonies were totally consumed and destroyed the colonies.
- Elevation: Up to 1800 m (6,000 ft)
- Rainfall: 600-2000 mm (24-78 in)
- Soil Types: tolerates a wide range of soil fertility, acidity (pH 5-6 preferred) and salinity
- Temperature Range: moderately high over long growing season
- Day Length Sensitivity: short days encourage bushiness, long days produce vining up to 2 m (6.5 ft).
Harvesting and Seed Production
If grown as a green manure, the seeds usually are broadcast. If grown as a food crop, the seeds may be planted 2-3 cm (0.75-1 in) deep, 30-45 cm (12-18 in) apart, in rows 60-90 cm (24-36 in) apart. Jack Bean thrives in warm humid environments with a long growing season of full sunlight but can produce a crop of beans in light shade. Green immature pods may be harvested 90-120 days after planting. Mature seeds may be harvested 180-300 days after planting by cutting the whole plant when the pods are brown and dry. The thick seed coat resists burrowing insects during storage.
Pests and Diseases
Jack Bean is relatively free of pests and diseases. Root rot, stem-borers and leaf-eating beetles pose problems in different stages of growth.
Cooking and Nutrition
Leaves, young branches, pods and seeds may all be eaten but they must be very young, tender and must always be thoroughly cooked and the cooking water drained. The mature seeds, sometimes eaten as “famine food” are not flavorful, have a mealy texture, require hours of soaking and boiling in water to soften and rid them of harmful toxins. They are however a nutritious source of protein and carbohydrates. The tough seed coat, that comprises 13% of seed weight, needs to be removed, after cooking. Jack Bean seeds sometimes are roasted and used as a coffee substitute. In Indonesia, steamed flowers and leaves are used as flavorings.