Unlike the potato, which is a tuber, or thickened stem, the sweetpotato that we eat is the storage root of the plant; an enlarged lateral root.
Sweetpotato is cultivated by vegetative propagation. Growers take stem cuttings from the vines, which then root and form new storage roots. In some colder climates, where vines do not develop well, producers will plant roots. Botanical seed is used in breeding programs.
The plant’s vine system expands rapidly horizontally on the ground, and planting material can be easily and quickly multiplied from very few roots. Roots mature on average about four months after planting, with some early maturing varieties ready at two months.
Storage roots vary in shape and size according to the cultivar and type of soil where they are grown. Skin color can range from whitish-cream, through yellow-orange and pink to red-purple and very dark purple. Flesh color can be white, cream, yellow, orange, or purple. Some cultivars have a base flesh color with specks or striations in a darker color.
The crop has relatively few natural enemies and grows well in poor soils. As the rapidly growing vines shade out weeds, it requires relatively little labor, fertilizer, or harmful pesticides.