Common Name: Asparagus Bean

General Information

Vigna unguiculata sesquipedalis is an annual climbing plant. Some forms are erect and bushy, whilst others produce climbing stems from 2 - 4 metres long that scramble over the ground or twine into other plants for support[].
The plant is often cultivated for its edible seed in warm temperate and tropical zones. An abundant cropper, it can produce a harvest all year round in the Tropics, especially if new sowings are made every few months[]. The large violet-blue flowers and draping pods make the plant a useful ornamental in city parks, office buildings, and around homes[].

Known Hazards

None known

Botanical References

,

Range

Original range is uncertain, perhaps tropical Africa

Habitat

Not known in the wild

Properties

Edibility Rating
Medicinal Rating
Habit	Annual Climber
Height	4.00 m
Pollinators	Insects
Self-fertile	Yes
Cultivation Status	Cultivated, Ornamental

Cultivation Details

Asparagus beans grow well in lowland tropical areas, and can also be cultivated at elevations up to 1,000 metres[]. They prefer a daytime temperature in the range 20 - 30°c, can tolerate 14 - 38°c[]. They grow badly at temperatures above 35°c and will be killed if temperatures fall to 4°c[, ]. Most cultivars grow well in humid conditions with an annual precipitation of 1,500 - 2,000mm, but can tolerate 650 - 4,100mm. Some cultivars will not flower during periods of heavy rainfall[].
Requires a sunny position[], Succeeds in a wide variety of soils, from sandy loams to clays, so long as they are well-drained[]. Good yields have also been obtained on peaty soils[]. Plants can tolerate moderate levels of salt in the soil[]. Prefers a pH in the range 5.5 - 7, tolerating 4.3 - 7.5[, ]. Dislikes alkaline soils since this reduces nodulation of bacteria on the roots and causes chlorosis of the leaves[].
Young seed pods can be harvested about 2 months after sowing, whilst mature seeds can be obtained in 3 - 5 months[].
Up to 6 tonnes of green pods can be obtained per hectare, or 400 - 750kg of dried seed[].
There are many named varieties[, ]. Most cultivars are day-length neutral, though short-day forms are also known[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[]. When removing plant remains at the end of the growing season, it is best to only remove the aerial parts of the plant, leaving the roots in the ground to decay and release their nitrogen.

Edible Uses

Seed - cooked[]. Rich in protein. It can be ground into a meal and added to breads, cakes etc[].The seed is 9 - 12mm long[]. The seed can be soaked in water and allowed to sprout, when it can be eaten raw or cooked in meals such as stir fry[].

Seedpods - raw or cooked[]. Usually harvested when around 25 - 30cm long, while the skin is still smooth and before the seeds expand[]. They can be used in salads, stir-fried, steamed and used as a vegetable[, ]. Sweet and crisp, with a delicious mushroom-like flavour[].The seedpods vary in length from 30 - 60cm and are about 12mm wide[].

Young leaves and shoots - cooked and used as a spinach substitute[].

The dried and roasted seed can be used as a coffee substitute[].

Medicinal

The crushed leaves are used in a poultice to heal and bond broken bones[].

Other Uses

None known

Propagation

Seed - pre-soak for 12 hours in warm water and sow 1 - 3cm deep[]. The seed can be sown in situ, but this will not work well in many parts of the temperate zone since it germinates best when the soil temperature is above 21°c[]. Alternatively, sow the seed in spring in medium-sized pots in a greenhouse, planting 2 - 3 seeds in each pot. Grow the plants on until well established and plant them out in a warm position once the danger of frost has passed.