Lablab

Lablab (Lablab purpureus) is a fast-growing annual warm-season twining legume vine native to sub-Saharan Africa and widely cultivated throughout the tropics. Also known as hyacinth bean or dolichos bean, it produces striking purple flowers and dark seeds on vigorous vines reaching 1–2 m. It fixes atmospheric nitrogen, making it valuable as a green manure and intercrop. The plant demands full sun, well-drained fertile soil with a pH of 6–7, and consistent heat to perform at its best.

Growing

Direct-sow seeds 2–3 cm deep into well-drained, fertile soil only once soil temperature is reliably above 20 °C. Space plants 40 cm apart in full sun. Germination takes 8–10 days. Provide a trellis, fence, or other climbing support immediately after sowing, as vines establish quickly. Avoid waterlogged conditions — the plant is highly susceptible to root damage from standing water. For green manure use, cut or dig in the vines once flowers are fully formed.

Care

Water moderately and consistently; Lablab tolerates some drought once established but requires at least 600 mm of rainfall equivalent per season. Do not allow soil to become waterlogged. Feed with a low-nitrogen fertiliser or legume inoculant at sowing to support nodule formation and nitrogen fixation. Train vines onto supports as they grow. In warm climates, monitor for and prevent unwanted self-seeding after the harvest period.

Harvest

Harvest young pods when they are tender and bright-coloured, before seeds swell fully inside — at this stage pods are suitable for cooking. For dry beans, allow pods to mature and dry fully on the vine before collecting. The harvest window extends over several weeks as the vine continues to flower and pod. All parts of the plant must be thoroughly cooked before consumption, as raw seeds contain toxic glycosides.

In the kitchen

Young pods can be cooked like green beans — boiled, stir-fried, or added to curries. Mature seeds, once fully cooked by boiling with water changes, are used in dals, stews, and traditional dishes across Africa and South Asia. The leaves and flowers are also edible when cooked. Always discard the first boiling water and cook thoroughly to neutralise toxic compounds.

Storing

Fresh pods keep for up to one week refrigerated in a sealed bag. Dry seeds store for 2–3 years in a cool, dry, airtight container away from light. Blanched and frozen pods keep for up to 12 months in the freezer.