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close this bookBetter Farming Series 16 - Roots and Tubers (FAO - INADES, 1977, 58 p.)
close this folderSweet potatoes
close this folderDescription of the plant
View the document(introduction...)
View the documentVarieties of sweet potato
View the documentWhere are sweet potatoes grown?


The sweet potato is a climbing herbaceous plant. It may live for several years, but often it is harvested after 3 months, without waiting for it to flower.

The stems may grow to 2 or 3 metres in length; they are thin and climbing or creeping. They have nodes at varying distances apart. It is thought that the varieties with short inter- nodes yield more heavily than those with long inter- nodes.

The leaves vary greatly in size and shape. Depending on the variety, they may be entire, heart- shaped or deeply divided with three, five or seven lobes. The leaf veins and the leaf- stalks are green or red.

The flowers, usually violet, sometimes white, are clustered in the leaf axils. Many varieties of sweet potato in cultivation do not have time to produce flowers and fruits before the harvest.

The most important part of the plant is the roots, because they can develop into tubers.

The tubers are parts of the creeping roots that have built up food reserves.

These tubers are produced at points where the roots cease to spread out near the surface and turn downward into the soil. By making mounds that are not too wide, the formation of tubers is helped.

Leaves and tubers of sweet potato

Varieties of sweet potato

Varieties of sweet potato differ greatly in the number, shape and size of their tubers and in the color of the peel and flesh of the tubers.

Sweet potatoes may be round or elongated. In colour they are white, yellow, red or violet, with soft or firm flesh. They may weigh between 0.3 and 3 kilogrammes.

Where are sweet potatoes grown?

- Climate

Sweet potatoes grow well in warm, sunny and humid regions. At the same time, they withstand drought very well. For that reason, they are suited to dry savanna country.

Sweet potatoes need regular rain to grow, especially when the leaves are coming into growth. But if there is too much rain at harvesting time, the tubers rot.

- Soil

The sweet potato will grow in poor soils. The most suitable soil is a light, well- drained, sandy loam. If the soil is too rich in organic matter and nitrogen, the plant produces a great deal of useless stem and leaves, and only after a long time produces a very few tubers.