Dolichos lablab is a twining vine with three purplish green leaflets per leaf and showy bright purple flowers which are followed by showy purple seed pods. They are grown as ornamental plants used as screens on a trellis or fence. They are fast growing and attractive in leaf, when flowering and when producing seed pods. Butterflies and hummingbirds like to visit the flowers. In other parts of the world they are consumed as a food source. In frost-free locations the stem of the vines becomes woody and they can grow 30 feet tall. In zones 2 threw 9, plants are herbaceous annuals and rarely grow taller than 10 feet tall. The pea-like flowers are showy purple color and arranged in loose clusters on long stems that grow above the foliage. The 3 inch long seed pods, which are like broad but thin pea-pods are as or more attractive than the flowers, they are a rich purple color. When the seeds are ripe the pods twist open and dry. The ripe beans inside the pods are black with a conspicuous white hilum, which is the point of attachment to the pod.
Many cultivars exist, including plants with white flowers and green pods, others have red flowers, some with long thin pods, and others are dwarf forms. Some forms are grown for pods, seeds or roots for eating. This species is native from Asia and is grown in many areas as a food source and as an ornamental vine on fences and posts. In some areas of the world it has escaped cultivation and can be found growing along shrub rows and in thickets. Immature seed pods must be cooked well and they are eaten like green beans. It has a strong bean flavor and scent, but the purple coloration disappears when cooked. Sometimes the fresh, new leaves are eaten raw in salads and older, tougher leaves are cooked like spinach. Flowers are eaten and root tubers are also eaten too. Dried seeds need to be boiled with more than two changes of water, because they contain toxic levels of cyanogenic glucosides . Do not eat the dry seeds without cooking, they are poisonous and if eaten raw, cause vomiting, labored breathing, convulsions and unconsciousness. You need to eat a good amount to be dangerous, but why take the chance?
Plants are easy to grow in poor soils, or in pots in a peat-perlite mix, they take 80-150 days to produce harvestable seed pods.In Asia and Africa were lablab is grown for food, this species is also grown as an excellent nitrogen fixer and as a feed for cattle. Grow in Full sun for best growth and color. Grow in well draining soils, water well until the plants are established, once established they are very drought tolerant. This twining vine with purple tinted stems and alternately arranged, pinnately divided leaves, and attractive pea-like flowers in elongated clusters, has flat bean like fruits that are curved, maroon or purplish in color with 3-5 black seeds.
Germination in one to three weeks at 75F, lightly cover seeds. Vines, do not start plants to early inside, they are fast growing.