When to Harvest Potatoes
Potatoes are among the most satisfying crops to lift, but the right moment depends on whether you grew earlies for tender new potatoes or maincrops for winter stores. Watch the foliage, flowering and skin rather than relying on a calendar alone, as weather and site conditions vary widely around the UK.
Start by identifying the type you planted. First earlies are usually ready from June to July in milder districts, often around 10 to 12 weeks after planting. Second earlies follow from July into August. For these, you are harvesting young tubers, so gently feel beneath one plant once it has flowered or as flowers fade. Lift a few potatoes when they are the size you want, then leave the rest for another week or two if they need more bulk. Use a hand fork well away from the stems to avoid spearing tubers. Harvest only what you will eat promptly, because newly lifted earlies do not store for long.
Maincrop potatoes normally need until September or October, although cool northern and Scottish gardens may be later. Wait until the tops have turned yellow and begun to die back naturally. This signals that tubers have largely finished swelling and are developing tougher skins for storage. If blight has damaged the foliage, cut it off at soil level and leave the potatoes underground for at least two weeks before lifting. That interval helps the skins set and reduces the chance of disease travelling from foliage to tubers. Do not leave them indefinitely in wet ground, however, because slugs, rot and waterlogging can spoil a promising crop.
Check skin set before committing to a full harvest. Rub a newly lifted potato gently with your thumb. If the skin scuffs away easily, leave the crop for another 10 to 14 days if weather permits. A firm skin is essential for stored maincrops. Choose a dry day after a spell without heavy rain, when soil is crumbly rather than sticky. Cut down the haulms first if they are still standing, then lift each clump carefully with a fork. Work from the outside inward, keeping the fork at least 30 cm from the main stems. Search the soil thoroughly for small tubers, which can become unwanted volunteer plants next year.
After lifting maincrops, leave sound potatoes on the soil surface for a few hours only if conditions are dry and shaded. Bright sunlight can turn exposed tubers green, making them unsuitable to eat. Move them under cover to dry gently, then sort them. Put aside any damaged, cut, diseased or very small potatoes for immediate cooking, and do not add suspect material to the compost heap. Keep only unblemished tubers for storage. Avoid washing them, as damp skins encourage rot. Brush away loose soil with your hands and allow the crop to finish drying in an airy, frost-free shed, garage or greenhouse staging protected from direct sun.
Store cured maincrop potatoes in breathable hessian sacks, paper sacks, wooden crates or dark cardboard boxes, with ventilation between layers. A cool, dark and frost-free place is best, ideally away from apples and other fruit that can encourage sprouting. Check the store every fortnight and remove any soft or mouldy tubers before they affect neighbours. First and second earlies are best kept for only a short time in a cool cupboard or refrigerator vegetable drawer, then used while their flavour is at its freshest. Label stored varieties if you grow several, as different potatoes keep for different lengths of time.
Plan the next harvest around your soil and local climate. In warm southern gardens, first earlies may be ready before midsummer, while exposed northern allotments can be several weeks behind. Heavy clay often stays wetter in autumn, so lift maincrops before persistent rain makes digging difficult. Light soils may allow a little more flexibility but need checking for drought-stressed tubers. Never harvest when soil is frozen. If a hard frost is forecast and your maincrops remain in the ground, protect the bed temporarily with a thick layer of straw, grass clippings or garden compost, then lift as soon as conditions improve.
Frequently asked questions
Can I harvest potatoes before the plants flower?
Yes. Flowering is a useful guide, not a requirement. First earlies can be checked once plants are vigorous and have been growing for roughly 10 weeks. Carefully loosen soil beside one plant and take a few usable tubers. If they are still small, replace the soil and wait another week or two.
Why are my lifted potatoes green?
Green patches develop when tubers have been exposed to light, either in the ground or after lifting. Cut away a very small affected area on an otherwise sound potato, but discard heavily green tubers. Earth up growing plants promptly and cover exposed potatoes with soil, compost or straw to prevent further greening.
Should I wash potatoes before storing them?
No. Washing leaves moisture in crevices and can shorten storage life. Let potatoes dry under cover, brush off loose soil and store only sound, dry tubers. Wash them immediately before cooking instead. This also makes it easier to spot any potatoes becoming soft or mouldy during winter.
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 18 Sep 2026.