Sweet potatoes are colourful, tasty and lower in calories than traditional potatoes. Modern varieties are bred for the British climate to produce a worthwhile crop of uniform roots.
Which to choose
Beauregard is the best variety for the UK climate. It’s compact and bears high yields of deep orange fleshed tubers that store very well.
When they arrive
Unlike traditional potatoes, Sweet Potatoes are grown from unrooted or partially rooted cuttings known as ‘slips’. (The average length of a slip is 8in/20cm). As soon as the slips arrive immerse them in a glass of water so that ¾ of the stem is submerged; leave them overnight to revive and firm up ready for potting on.
Pot up each slip into a deep container; it’s important to cover the stems completely right up to the first leaves. Leave them for 8-12 days to kick start the roots into growth. Keep them somewhere warm and frost free.
Prepare the soil
Prepare the soil prior to planting in late April/May; make sure it is well drained and aerated. Good drainage is essential so plant in a raised bed if you garden on heavy soil. Not too much nitrogen required.
Plant the rooted slips 1ft/30cm apart, at an angle of less than 45 degrees. Sweet potatoes are scrambling plants (members of the Ipomoea family) so give them space to grow. Allow 3’ between rows.
For the best results and to develop maximum sweetness, grow in full sun.
Harvest and Store
Plants are ready to harvest 120 days after planting, expect to harvest the tubers in October once the leaves turn yellow and die back. The tubers can stay in the ground longer but harvest before the first frosts. Lift in the same way as potatoes and let the skins toughen by leaving them in the sun for a few hours, move to a bright humid place such as a greenhouse for a week or so, to help storage.
5 slips should give at least 5kg -10kg of sweet potatoes depending on location. In the north expect to get 1-2kg of sweet potato tubers per slip, in the warmer south it should be in excess of 2kg per planted slip.
Store sweet potatoes somewhere cool once tubers are completely dry.