Mung bean plants (Vigna radiata) are versatile legumes originating from the Indian subcontinent, cultivated globally for their edible seeds and sprouts. Gardeners find understanding their appearance helpful, whether for culinary use or as a nitrogen-fixing cover crop. These warm-season annuals produce protein-rich beans used in various dishes.
Characteristics of a Mature Mung Bean Plant
A mature mung bean plant stands between 0.5 to 1.3 meters (1.6 to 4.3 feet) tall, with some varieties being more erect or semi-trailing. It has a branched stem, green or purple when young, maturing to grayish-yellow or brown. The well-developed root system includes a sturdy taproot and lateral roots with nitrogen-fixing nodules.
Mung bean leaves are trifoliate, meaning each leaf comprises three distinct leaflets. These oval or broad-ovoid leaflets measure 6 to 12 cm long and 5 to 10 cm wide. Small, pale yellow or greenish, pea-like flowers emerge in clusters of 10 to 25, often found near the top of the plant or in leaf axils. These self-pollinating flowers simplify the reproductive process.
After flowering, elongated, cylindrical pods develop, usually 7.5 to 10 cm (3 to 4 inches) long. Each pod contains 10 to 15 seeds, with a single mature plant producing 30 to 50 pods. As they ripen, pods change from green to yellowish-brown, black, or pale gray, and may develop a fuzzy texture. The seeds inside vary in color, including yellow, green, brown, or black.
Optimal Conditions for Mature Growth
Mung bean plants thrive in warm conditions, needing a 75 to 120-day frost-free period to mature. The ideal temperature range is 20 to 30°C (68 to 86°F), though they tolerate up to 36°C (96°F). Plant when soil temperatures consistently remain above 15°C (59°F).
Full sunlight exposure, ideally 6 to 8 hours daily, benefits plant development and pod formation. While partial sun is tolerated, yield may reduce. Mung beans perform best in well-draining, fertile sandy loam soils with a pH of 6.2 to 7.2. Heavy clay soils, especially those prone to waterlogging, are unsuitable.
Consistent moisture is important, particularly during flowering and pod development. Mung beans need 5 to 7.5 cm (2 to 3 inches) of water per week, supplied through regular watering sessions. Watering at the plant’s base helps prevent fungal issues. Proper spacing, with seeds 5 to 10 cm (2 to 4 inches) apart within rows and 75 to 120 cm (30 to 48 inches) between rows, allows for ample air circulation and development.
Harvesting Full-Grown Mung Beans
Mung beans mature within 75 to 90 days after planting, though pod maturity is often not uniform. Harvest begins when about one-half to two-thirds of the pods are mature. A key visual cue is the change in pod color, turning from green to dark brown or black. Mature pods may also become fuzzy and dry.
Harvesting can be done by hand, picking individual pods as they ripen, or by pulling up the entire plant once most pods are ready. If harvesting the whole plant, hang it upside down in a cool, dry area like a garage or shed to allow remaining pods to dry. Laying fabric or newspaper beneath can catch falling beans.
Once harvested, pods become thin and brittle, making beans easy to shell. The seeds can be dried further on newspaper until their moisture content is suitable for storage. Properly dried mung beans can be stored for several years without issue, providing a long-lasting food source.