They are cultivated in tropical and subtropical Africa and Asia. A plant of the moist tropics adapted to the monsoon. It grows best in areas where annual daytime temperatures range from 17 - 27°c but can tolerate 8 - 36°c [418 ]. Lower night temperatures promote tuber development [300 ]. It prefers a mean annual rainfall in the range 1,800 - 2,600mm, but tolerates 1,200 - 4,000mm [418 ]. Plants are adapted to relatively high rainfall - the best yields are obtained in areas with rainfall well distributed through the growing season [300 ]. They require regular moisture during the summer growing season and especially when their tubers are fattening during autumn. Resist the temptation to overwater tubers when they are newly reawaken in the spring, plants progressively become more thirsty as they generate an increasing volume of foliage. Harvest in early winter. When there is too much rain, the tubers tend to branch, which consumers dislike because they are then difficult to peel [299 ]. Requires a sunny position [299, 418 ]. It prefers a well-drained sandy loam but can tolerate a range of soils [300, 418 ]. Tolerant of poorer, dry soils, though yields are lower in such conditions [299 ]. Yields are low in heavy soils [299 ]. Prefers a pH in the range 6.5 - 7.5, tolerating 5.5 - 8 [418 ]. Dislikes waterlogged soils [300 ]. Plants take 5 - 7 months from planting to harvesting the tubers[300 ]. The tubers are formed on stems that are in contact with the soil. Yields from 7 - 15 tonnes per hectare have been recorded [300 ]. The tubers need to be harvested quickly, or they are liable to decay rapidly [300 ]. Hausa potato is difficult to store. Traditionally the tubers are stored in the ground under a tree where it is cooler than in the open. When stored in this way under hot conditions, the special taste of Hausa potato usually lasts for two months only, after which the tubers become bland and are no longer considered a delicacy [299 ]. Hausa potato is also packed in bags or baskets stuffed with straw, but if these are kept under warm conditions, the tubers will soon shrivel and are no longer edible. To keep the tubers longer, people put them in pots sealed with cow dung. The small tubers needed for the next planting season are stored in this way. In cooler conditions, such as in highland regions of South Africa, storage is easier[299 ]. There are some named varieties[300 ]. Plants wither and become dormant, and die down during the cool season. Hausa potato can be easily grown in soil or containers and often grown as an annual crop especially in more temperate areas. Leaves are slightly oily and aromatic, giving a peculiar aroma that resembles black pepper.