Eat them roasted, mashed, baked or fried – Sweet potatoes make a delicious alternative to the humble spud. In recent years their popularity has soared and they are easily found in the supermarket. But supermarket ranges are limited, and with so many different coloured varieties to choose from, it makes sense to grow your own sweet potatoes.
Sweet potatoes are traditionally grown in warmer climates but don’t be put off. New, hardier cultivars mean that now you can grow sweet potatoes in the UK.
This video shows you how to root sweet potaotes. Homegrown sweet potatoes often taste sweeter than those bought from supermarkets.
This video shows you how to grow sweet potatoes
The sweet potato is a member of the Ipomoea family; the same genus as the popular flowering climber ‘Morning Glory’. They are low fat, containing only 90kcal per 100g, and loaded with carotenoids, vitamin C, vitamin A, potassium and fibre. The leaves and tips of young shoots can even be cooked as a spinach substitute. In fact Sweet Potatoes are the healthy-eating superstars of the root vegetable world!
- Sweet potato plants are not hardy so you will need to grow them on in warm, frost free conditions for 3 weeks or more until they are established. Warm, humid conditions will quickly encourage the slips to produce roots. Once they are well grown, and all risk of frost has passed, gradually acclimatise sweet potato plants to outdoor conditions prior to transplanting them.
- Sweet potatoes need high temperatures of 21-26C (70-78F), and their long stems need plenty of space as they have a vigorous growth habit. When growing sweet potatoes in the UK, they are best planted in greenhouse borders, polytunnels or under cloches if you live in a cold area. In milder areas they are well worth trying outdoors, planted through a sheet of black polythene to warm the soil and suppress weed growth. Cover them with fleece or plastic cloches – you’ll be amazed the difference that this will make to the temperature.
- Grow sweet potatoes in full sun on fertile, well drained soil. They are not particularly fussy but do prefer an acid or neutral soil. Plant sweet potatoes 30cm (12″) apart, leaving 75cm (30″) between each row. Where space is limited you can even grow sweet potatoes in containers or patio bags.
Growing sweet potatoes
Water sweet potato plants regularly. If growing your crop undercover, remember to open doors and windows during the day to keep your greenhouse or polytunnel well ventilated. Greenhouse and container crops will also appreciate a feed of general purpose fertiliser every two or three weeks.
Sweet potatoes have a vigorous growth habit and long sprawling stems. In the greenhouse it may be useful to train the stems onto strings or trellis to keep them tidier. Outdoors you can simply spread the stems out around the plant. Pinch out the growing points of stems that extend beyond 60cm (2’) to encourage more lateral stems to develop.
Harvesting sweet potatoes
In late summer, approximately 12 to 16 weeks after planting them, you will notice that the foliage and stems begin to turn yellow and die back. Now is the time to start harvesting your sweet potatoes, although they can be left in the ground longer if you prefer larger tubers. Make sure that you lift them before the first frosts though, to avoid the tubers being damaged by the cold. Lift them with a fork taking care not to bruise them.