Sword Bean

Other common names: 刀豆

Sword beans are impressive vines that produce bean pods that can be up to 35cm long and 6cm wide, resembling the blade of a sword. Young pods, leaves and stems can be eaten raw, steamed or boiled. Mature beans can also be eaten but should be boiled in at least two changes of water and have their seed coats removed due to toxic proteins within the mature seeds.

As a perennial vine, it is an uncommon sight in edible gardens.

This plant is part of the Fabaceae or bean family, which includes other popular edible fruits like winged bean, peanut, and long bean. All members of the bean family can be used for companion planting as they can fix nitrogen into the soil.

Sun and soil needs:

This vine does best in full sun gardens with a minimum of 6 hours of sunlight. It can also grow in areas with at least 6 hours of indirect sunlight but will produce less fruit.

Plants do best in pots with loamy soil at least 30cm deep, or in true ground.

This vine is vulnerable to heat stress during the dry season. Water it regularly and mulch the base to prevent water loss.

Sowing seeds:

Seeds can be sown directly into pots or the ground around 15-30cm apart. Lightly water the soil until damp, once a day. Seeds should sprout within 10 days.

The seedlings are generally resilient to most environmental factors but may be vulnerable to being eaten by birds or snails. Grow seedlings till they are at least 10cm tall before planting them in true ground, or use DIY cloches or netting to protect young plants.

Growing:

Bean plants generally do not require much fertilising because they are able to fix their own nitrogen. The can will however produce more flowers and thus more fruit when fed with fertilisers high in phosphorus and potassium. Plants can be fertilised regularly once a month after the first flower for a fuller crop.

Because the vines will grow on top of each other, it is a good practice to prune regularly and remove dead leaves and vines to improve ventilation and allow light to reach more of the plant.

As a fast-growing vine, this plant can be grown on the ground or trained up a sturdy trellis. The fruits are quite long and often exceed 30cm, so they do best on tall trellises.

Harvesting:

Plants can be harvested for young leaves and stems or immature fruits at any time.

Pods are mature when they turn dry and brown. The pink beans can only be eaten after being boiled at least twice, with water being changed each time. Beans from mature pods can also be used for future planting.

Harvest cycle:

Propagation:

This vine can be grown via seeds. Seeds can be taken from mature fruit for immediate planting.

Common problems & solutions:

Young plants have soft stems and can be completely eaten by slugs and snails. Grow seedlings till they are at least 10cm tall before planting them in true ground, or use DIY cloches or netting to protect young plants.

If your plant has few to no flowers, you can fertilise the plant with fertilisers high in phosphorus and potassium. These nutrients encourage root and flower growth, which are important for the plant to produce more fruit.

Aphids, mealy bugs, whiteflies, and spider mites often infest the plant if it has underlying problems like repeated wilting from heat stress. Mechanical pest control methods like pruning the infested parts are the best methods for managing these pests in the short term, but resolving the underlying problem will prevent them in the long term.

Wilting leaves during hot weather is a sign of heat stress. Increase the number of times the plant is watered daily, and apply mulch at the base to prevent water loss.

Squirrels and birds may eat unripe or ripe fruit. Wrap your fruit in netting when it starts to develop from a fertilised flower, ideally after all the petals have dropped off.