Sweet potatoes are related to morning glory and not ordinary potatoes. It’s possible and fun to grow your own. Plants are usually raised from ‘slips’ taken from sprouting tubers. You can sometimes buy them online or in a garden centre; ‘Beauregarde’ and ‘Georgia Jet’ (with orange flesh) and ‘T65’ (white flesh) are suitable varieties. ‘O’Henry’ produces tubers close to its base and is good for container growing.
Bought tubers can be from varieties less suitable for Irish conditions, but you can still get a small crop from their shoots. Organic tubers unsprayed with sprout inhibitor are best. Stand the tubers half-submerged in lukewarm water with their narrow ends down. Place them in a warm sunny spot to sprout, changing the water daily. Cut off the sprouts when they are about 15cm long. If still rootless, root them in warm water or cutting compost and plant when rooted. Soak bought-in slips overnight in lukewarm water before planting.
Plant them deeply (to encourage tubers to form at the nodes) in light, well-drained, fertile, neutral or acid soil in full sun. Always keep plants and tubers above 10°C/50°F. Give warmed water when needed, and feed weekly with tomato feed. Tie up the sprawling stems or they will root into the ground at the nodes. Green leaves can be eaten in salads or lightly cooked like spinach, but don’t take too many or you will reduce the tuber crop. Dig up the tubers after 3-4 months when the foliage turns yellow and dies back. Avoid damaging them as they bruise easily. Dry the roots in the sun for a few hours and then cure them for five days at 30-32°C / 85-90°F and 85-90% humidity. Store them above 10°C/50°F in good ventilation and either eat them soon or blanch and freeze them.