Sweet potato, despite its name is not related to the potato but is a member of the bindweed family; and as its name suggests, it’s a good deal sweeter than the ordinary potato.
The sweet potato was probably domesticated in Mexico but possibly in South America, some 8,000 years ago. Much later, after Columbus discovered the New World in 1492, European sailors introduced the sweet potato to Africa and then Asia. Interestingly, the sweet potato was being grown in Oceania before Columbus, but the routes of introduction are still debated. As it’s a semi-tropical plant it must be planted under protection, either glass or plastic. Grows best at 21-26°C.
Sweet potato is grown from slips or rooted cuttings (plug plants) which can be purchased. To produce your own slips get a tuber and stick it in peat in a warm glasshouse and it should produce 10-15 cm sprouts in 4 or 5 weeks. Take a cutting and put it into a small pot covered with a plastic bag – burying it 2-3 nodes deep. Grow in a warm place for about 3 weeks until established. It will root from the cut stem area and also from the nodes.
Plant on a shallow mound at 30x75 cm spacings under protection in late May to early June. Density is 4.5 per square meter. Takes 100 to 120 days to maturity. Pest and disease not generally problematic but keep an eye out for aphids. Slugs can graze the tubers and red spider mite can feature along with sclerotinia if either of these two are present in the glasshouse or polytunnel. In early autumn when you notice the crop beginning to turn yellow and die back, harvest the tubers. You can leave them to get bigger but they need to be lifted before the first frosts.
Evangelina (orange), Beauregarde (orange), Bonita (white)