Common Name: Sweet Potato

General Information

Ipomoea batatas is a vigorous scrambling or climbing perennial plant producing stems 4 metres or more long from underground tubers. These stems can scramble over the ground or twine into other plants for support. Where the stems lay along the soil they will root at the nodes and form tubers[]. The plant was developed in cultivation, probably from the central American species Ipomoea trifida[].
One of the most widely grown root crops in the tropics, where it is a staple food. It is one of only seven world food crops with an annual production of more than 100 million metric tons[]. The root is also used as a source of an industrial starch[].

Known Hazards

None known

Botanical References

Range

Pantropical - originating in northern S. America and Mesoamerica.

Habitat

Derived in cultivation, probably from Ipomoea trifida, this species is not known in a truly wild situation.

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial Climber
Height	3.00 m
Growth Rate	Fast
Cultivation Status	Cultivated

Cultivation Details

Sweet potato is a plant of the tropics, but can also be grown in the subtropics and, if there is a sufficient growing season of 110 - 170 days, as an annual crop in warmer parts of the temperate zone. It is grown in the tropics at elevations up to 2,800 metres. It grows best in areas where annual daytime temperatures are within the range 18 - 28°c, but can tolerate 10 - 38°c[]. When dormant, the roots can survive temperatures down to about 1°c, but young growth can be killed by temperatures of 5°c[]. It prefers a mean annual rainfall in the range 750 - 2,000mm, but tolerates 350 - 5,000mm[].
An easily grown plant, it prefers a well-drained, sandy loam soil and requires a sunny position[, ]. Ample potash in the soil is essential for a good crop[]. Prefers a pH in the range 5 - 7, tolerating 4 - 8.7[]. A low humidity as the plants reach maturity is beneficial[].
Plants grow very vigorously in the tropics. They have escaped from cultivation in some areas and become invasive[, ].
Unlike many root crops, the sweet potato begins to store starch at an early age, making early harvests possible[]. It is one of the most efficient plants to capture the energy of the sun as calories[].
The plant can mature a crop within 2 months in tropical areas, though at least three months are required in sub-tropical regions[].
Optimum yields vary from 17.5 - 27.5 tonnes per hectare depending on the cultivar and growing conditions, while average yields are 5 tonnes per hectare in Africa, 10 tonnes in South America and 16 tonnes in Asia. The world highest production yield at 80 tonnes has been obtained in Israel[].
A short-day plant, it requires less than 11 hours of sunlight per day to initiate flowering[]. However, day length variation appears to have little effect upon tuber production[].

Edible Uses

Root - cooked[]. Sweet and fleshy, it is a delicious staple food and is also very nutritious providing a rich source of vitamins and minerals[, ]. There are cultivars with soft, moist flesh and also forms with a more dry flesh[]. There are also less sweet cultivars, bred for industrial production of starch[]. In order for the roots to store through the winter, they need to be cured in the sunshine at temperatures around 25°c for about a week before being stored at around 14°c[].

Young shoot tips[, ]. Cooked[]. Used as a spinach[].

Medicinal

The leaves are used to treat measles[].

Other Uses

The root is a source of starch[].

Sweet potato tubers are being examined as a valuable raw material for producing alcohol bio-fuel[].

Propagation

Pre-soak the seed for 12 hours in warm water, or scarify the seed, and sow in individual pots in a greenhouse in early spring. The seed usually germinates in 1 - 3 weeks at 22°c. Plants are extremely resentful of root disturbance, even when they are quite small, and should be potted up almost as soon as they germinate. Grow them on in the greenhouse for at least their first winter then plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Seedlings can be very variable and are likely to be less productive than vegetatively produced plants[].
Stem cuttings obtained from terminal shoots[]. Remove the lower leaves and insert the cuttings to half their depth in individual pots.