Potatoes are ready when the flowers open, or when the leaves die back

Potatoes tell you when they’re ready. First earlies are ready when the plants flower, about ten weeks after planting, which in most UK gardens means June. Maincrop potatoes are ready once the leaves and stems have turned yellow and died back, usually from late August into October.

The type on the seed potato bag matters more than anything else, because each type is grown to a different finish.

Ready times by type

Type	Weeks after planting	Usually lifted	Sign to look for
First earlies	About 10	June to early July	Flowers opening
Second earlies	About 13	July to August	Flowers open, lower leaves yellowing
Maincrop	15 to 20	Late August to October	Leaves and stems dead

These timings assume potatoes planted from mid-March to late April, as they are in a typical lowland English or Welsh garden. In Scotland, the north and frost pockets everything runs two or three weeks later, because planting waits for the soil to warm. In mild coastal gardens in the south-west, earlies can be lifted in late May.

New potatoes: dig when the flowers open

New potatoes are earlies lifted young, when the skins are thin enough to rub off with your thumb. You don’t have to wait for the leaves to die. Once the plants start to flower, scrape back the soil at the base of one plant with your hand. If the tubers are the size of a hen’s egg, they’re ready.

Lift earlies as you need them. They don’t store well, and the ones left in the ground keep growing bigger for a few more weeks, which is no bad thing if you like a larger potato.

Maincrop: let the skins set

Maincrop potatoes are grown for storing, and storing needs firm skins. When the foliage has yellowed and collapsed, cut it off at ground level and leave the tubers in the soil for another ten days to two weeks. The skins thicken in that time, which means fewer bruises and far better keeping.

If blight strikes in late summer, with brown patches on the leaves and stems collapsing within days, cut all the foliage off straight away and burn or bin it. Wait two weeks, then lift. That stops the spores washing down onto the tubers.

Doing a test dig

If you’re not sure, dig one plant. It costs you very little.

1. Pick a plant at the end of a row.
2. Push a fork in well away from the stem, at least 30 cm out, so you don’t spear the tubers.
3. Lever up the whole root ball and sift through the loose soil with your hands.
4. If the potatoes are small and the skins slide off easily, give the rest of the row another week or two. For maincrop, rub a tuber with your thumb: if the skin doesn’t move, they’re ready.

Lifting and storing

Dig on a dry day if you can. Lay the potatoes out on the soil surface for a couple of hours so the skins dry, but no longer, as light turns them green.

Store only sound, unmarked tubers. Brush off the loose soil rather than washing them, and put them in hessian or paper sacks somewhere dark, cool and frost-free. Check them every few weeks and take out any that have gone soft. One rotten potato can spoil the sack.

Go over the bed carefully when you’ve finished. Any tubers you miss will sprout next spring among whatever comes next, and can carry disease forward. That bed is now ready for the next crop in the rotation; our crop rotation planner shows what should follow, and what to plant after potatoes explains why.

Common problems at harvest

Holes in the tubers. Small round holes with a cavity inside are slug damage, worst in wet years and heavy soil. Lifting maincrop promptly helps. Narrow tunnels are wireworm, common in ground that was recently grass.

Scab. Rough, corky patches on the skin. It’s only skin deep, so peel and eat them. Scab is worse in dry, light, alkaline soil, so water during dry spells while the tubers are forming.

Hollow heart. A hole in the middle of a large potato, caused by a growth spurt after drought. Eat them anyway.

For planting dates, see when to plant potatoes. VegLog’s harvest journal keeps a record of what each row gave you, so you can compare varieties from year to year.