Of the many known African indigenous vegetables, African nightshade (managu) is arguably the most popular.
According to leading indigenous African vegetables researcher and horticulturalist Prof Mary Abukutsa-Onyango, there are two main types of African nightshade grown and consumed in Kenya — Solanum scabrum (broad leaved and with large purple berries) and Solanum villosum (with elongated leaves and orange berries).
The type with broad leaves is more popular and most promising in Kenya. Its origin is believed to be Africa and belongs to the same family as Irish potatoes and tomatoes, Solanaceae.
Abukutsa says the plant grows in a wide range of soils and is found throughout Kenya in the lowland and highlands. It does well in soils with high water retention capacity, well aerated and high in organic matter content with pH of 5.5 to 6.8.
The crop requires moderate rainfall especially during the vegetative stage. Too much rain will enhance the spread of fungal diseases. The temperature range of 18 to 30°C has been shown to be ideal for growing this vegetable with high light intensity. The plant cannot withstand frost but can tolerate partial shading.
The seed of nightshade is used for propagation, although it is possible to use stem cuttings. Seeds can be direct seeded or raised in the nursery and transplanted. Nursery raising is recommended, where seeds are first sown in a well-tilled seedbed to a fine tilth and sterilised by solarisation or heat generated by burning a layer of organic waste on top of the bed.
Manure maybe applied at the rate of about 15 to 20 tonnes per hectare. The small seeds should be drilled in rows 30 cm apart at a depth of 2-3 times the diameter of the seed after mixing it with dry sand or soil at the ratio of 1:10 and covering with a thin layer of fine soil, mulched and watered gently.
Germination occurs after 7 to 14 days. The mulch should be removed once the seedlings have emerged from the soil. The seedlings should be transplanted after hardening them when they have at least six true leaves or when they are about 15 cm (6 inches) tall or 6 weeks after sowing, at a spacing of 30 to 60 cm x 30 to 60 cm, depending on the variety.
Alternatively, the seeds can be direct seeded in a well prepared seed bed and thinned at four weeks after sowing to the above spacing. There may be a need to thin plants several times before the desired spacing is achieved. Thinned plants may be used for transplanting elsewhere but may also be consumed or sold.
In both direct seeded and nursery raised plants, the crop must be kept weed-free by light and shallow cultivation especially during the early growth period but once the crop canopy has formed, it should be kept minimal.