When to Harvest Sweet Potatoes
Sweet potatoes need warmth and a long growing season, so a successful UK crop deserves careful handling at harvest. Lift the tubers in autumn before frost, once growth slows and weather cools. Then cure them warm and humid for a short period, which improves skin toughness, flavour and storage life.
Plan to harvest sweet potatoes in September or October, before the first frost blackens the foliage or chills the soil. In a warm southern garden, greenhouse or polytunnel, plants may continue growing later than those outdoors in northern Britain. Do not wait for the leaves to yellow completely, because cool wet soil can damage tubers before the tops give a clear signal. Check one plant if it has grown well for at least several months. Gently scrape soil aside at the edge of the root zone to assess tuber size, then cover it again if they need more time. Harvest when usable tubers have formed, not solely by calendar date.
Choose a dry day if possible, and stop heavy watering several days beforehand so soil is easier to handle. Cut vines back to around 15 cm above the ground, then use a border fork well outside the original planting position. Sweet potato tubers can spread widely and are easily punctured, so begin at least 30 cm from the crown and lift the whole area gently. Use your hands to search through loosened soil. Avoid pulling hard on the stem, which can snap tubers underground. Lift each tuber carefully and set it down without dropping or knocking it against a bucket.
Handle freshly lifted sweet potatoes as though their skins were very delicate, because at this stage they are easily bruised. Do not wash them or rub soil off vigorously. Brush away only loose soil with dry hands and put damaged tubers aside for early use. Leave sound tubers to air-dry briefly under cover, never in cold rain or strong direct sun. Unlike ordinary potatoes, sweet potatoes benefit from a warm curing period. This closes minor wounds and helps the skins become tougher. The crop will not store well if it is chilled, wet or repeatedly handled during the first few days.
Cure sound tubers for around 7 to 10 days in a warm, humid, airy setting, ideally close to 25 degrees C. A warm greenhouse, insulated propagating area or suitable room can work, provided tubers are protected from direct sun and temperatures do not fall sharply overnight. Arrange them in a single layer on paper or trays with spaces between each one. Check daily for softness, mould or damp patches, removing affected tubers promptly. If you cannot achieve ideal warmth, give the crop the warmest stable frost-free conditions available and expect a shorter storage period.
After curing, store sweet potatoes at a moderately warm, dark, dry temperature, not in a refrigerator or cold shed. A cool cupboard indoors is often more suitable than an unheated outbuilding, as chilling injury can develop below about 12 degrees C. Place tubers in paper-lined boxes or baskets where air can circulate, and do not pile them deeply. Check every week or two, using any soft, damaged or sprouting roots first. Keep them separate from very damp produce. With good curing and careful storage, sound tubers can last for several months, although variety and growing conditions make a real difference.
Increase your chances next year by starting slips after the last spring frost has passed or by raising them under protection, then planting only when soil is reliably warm. Use a sunny, sheltered bed, raised bed, greenhouse border or polytunnel, enriched with garden compost but not freshly manured. Black mulch or a cloche can warm outdoor soil in cool regions, while fleece helps early establishment. Water regularly while plants root in, then avoid prolonged waterlogging. Record planting and harvest dates, because this will show whether your local site provides enough season for a worthwhile crop and which varieties perform best.
Frequently asked questions
Can I eat sweet potatoes straight after lifting?
Yes, but they usually taste better after curing. Freshly lifted tubers are edible, yet curing allows the skin to heal and the flavour to develop. Keep damaged tubers separate and use them first, as they are less likely to benefit from curing or to store successfully.
What happens if frost reaches sweet potato plants?
Frost can quickly damage foliage and may chill tubers in shallow soil, reducing storage quality. If frost is forecast, lift the crop beforehand. After an unexpected light frost, harvest promptly and inspect tubers carefully. Use any with soft, wet-looking or damaged areas first rather than trying to store them.
Why should sweet potatoes not be refrigerated?
Cold conditions can cause chilling injury, leading to poor texture, discolouration and a reduced storage life. Store cured sweet potatoes in a dark indoor cupboard or another moderately warm, dry place instead. Unlike ordinary potatoes, they are not a crop for a cold garage, shed or refrigerator drawer.
General guidance for UK home gardens and allotments. Conditions vary by region, soil and season; the RHS or a local garden centre can give site-specific advice. Page updated 19 Sep 2026.