Sweet potato, a vegetable that has seen increased interest over the last decade, has swiftly become a staple of the British dinner plate.
A potato indigenous to South America has in recent years been cultivated more and more in the UK. Due to its intolerance to frost, sweet potato particularly likes the temperate climes of the South West as Peter Adams from RHS Rosemoor explores further…
“The name sweet potato is somewhat misleading for this versatile and interesting to grow crop. For one, it isn’t related to the common potato in any way. It comes from the same genus of plants as the common garden annual morning glory and invasive bindweed, which are more commonly found taking over neglected gardens and allotments. Unlike bindweed, sweet potatoes won’t take over, they are tender and the first frost will quickly kill them off. Growing sweet potatoes is an enjoyable challenge, one we take on each year here at RHS Garden Rosemoor and while you may not achieve the large imported supermarket-sized crop, you should, with luck, get some good sized sweet potatoes to cook with.
Originating from South America, sweet potatoes need a good warm summer to flourish, which the British climate cannot always guarantee. Growing in a polytunnel will provide the warmth they need to produce a good crop. However, this is not an option everyone has, instead you can try growing them through black polythene. This will help heat the soil up further and retain this heat for longer, as well as holding on to important soil moisture.
Unlike the conventional potato, it isn’t as easy as just planting a tuber and off it grows. The easiest way is to buy pre-prepared young plants, which are cutting or ‘slips’ that have been grown especially for growing at home. These are readily available online from most major seed companies. These young plants will generally arrive around May and are best planted with the root laid horizontally, just under the soil surface. They must be kept well-watered but not saturated throughout the growing season. They will also need plenty of room to grow as the foliage will scramble along the soil surface. You could try and train them vertically if space is tight.
Towards the end of the growing season, the foliage will yellow and be killed by the first frost. Gently lift the sweet potatoes straight after, as leaving them any longer may risk the tubers being damaged by successive harder frosts. Sweet potatoes will store well for a few weeks, providing the skins are allowed to dry for a few hours after lifting and to cure for a few days somewhere warm and light. They should then be stored where it is cool and dry, allowing you time to make the most of them in the kitchen. There are more and more varieties becoming available in an array of colours, ‘Beauregard Improved’ and ‘Carolina Ruby’ are two varieties that have proved well at Rosemoor.”