When to Harvest Potato Plants

Potato plants are typically ready to harvest in the UK between June and October, depending on the variety and planting date. Early potatoes are harvested around 10 to 12 weeks after planting, often from late June through July. Maincrop varieties take longer, around 18 to 20 weeks, and are usually harvested between late August and October. The best time to lift them is when the plants start to die back and the foliage yellows and withers.

When and How to Harvest Potato Plants

For early potatoes, harvest once the flowers open or buds drop—this is a reliable sign they’re forming tubers. Gently dig around the base to check if the potatoes are big enough. For maincrop potatoes, wait until the foliage has fully died back, then leave the tubers in the ground for up to two weeks to allow the skins to set. This helps them store better. Use a fork or hands to lift the crop gently, being careful not to puncture the tubers.

Why Harvest Timing Matters

Harvesting at the right time affects the quality, flavour, and storage life of your potatoes. Too early, and they’ll be small and immature. Too late, and they risk disease or slug damage, especially in wet soil. Timing also impacts the skin's toughness—important for storage. Letting the skins mature in the soil before lifting gives them a better chance of lasting through winter.

Harvesting Benefits

Getting your timing right means firmer, tastier potatoes with better cooking quality. You’ll also reduce losses from rot or pests. Lifting potatoes during dry conditions makes them easier to clean and less prone to damage during handling. Harvesting in batches also helps manage yield and avoid waste, especially with larger maincrop varieties.

When to Harvest

The variety guides the harvest date. First earlies are usually ready in 10–12 weeks, second earlies in 13–15 weeks, and maincrops in 18–20 weeks. If you’re unsure, check the foliage: when it turns yellow and collapses, it’s a good sign the crop is mature. Always check the soil isn't too wet before harvesting—lifting in soggy conditions can bruise or rot the potatoes.

Instructions

Choose a dry day and use a garden fork to loosen the soil around the plant. Gently lift the tubers, starting at the outer edges and working inwards. For earlies, harvest as needed for fresh eating. For maincrop, once lifted, let them dry on the surface for a few hours. Brush off excess soil but don’t wash them—moisture encourages rot in storage.

Curing and Storing Potatoes

After lifting maincrop potatoes, cure them by storing in a dark, dry space for 10–14 days. This toughens the skin and improves longevity. Once cured, store in breathable sacks or paper bags in a cool, frost-free, dark place like a shed or cellar. Avoid storing with apples or onions, which give off gases that affect flavour and sprouting.

Should You Leave Potatoes in the Ground?

You can leave maincrop potatoes in the ground for a couple of weeks after the foliage dies back to allow the skins to set, but don’t wait too long. Wet or cold soil increases the risk of rot and slug damage. If bad weather’s on the way, harvest earlier and cure them indoors.

What Happens If You Don’t Harvest Potatoes?

Unharvested potatoes may regrow the next year, but quality often declines. Left too long in the soil, they can rot, sprout prematurely, or attract pests. They also interfere with crop rotation and can spread disease. It’s always better to lift the crop, even if you’re late—many are still salvageable.

Early vs Maincrop: Know the Difference

Understanding your variety is key. Early potatoes are bred to mature quickly and are best eaten fresh. They have thin skins and don’t store well. Maincrop potatoes are grown for size and storage, with thicker skins and a longer growing season. Mixing varieties in your garden means you can enjoy fresh potatoes early in the summer and have a stash to carry you through winter.

Signs of Readiness Beyond Just Dates

While the general rule is to count weeks from planting, visual cues are more reliable. For early potatoes: look for flowers. Once they bloom or drop off, the tubers are likely ready. For maincrop potatoes: wait until the foliage fully yellows and dies back. If you're unsure, carefully dig up a plant and check the size and skin maturity—rub a potato with your thumb. If the skin stays on, it’s ready; if it rubs off, give it more time.

Weather and Soil Conditions Matter

Lifting potatoes in wet conditions risks damaging the soil structure and causing bruising or rot. Aim for a dry spell if possible. Wet soil also sticks to tubers, which makes it harder to store them clean. If rain is forecast and the plants are ready, it’s better to harvest and cure indoors.

Curing Potatoes Improves Storage

Curing isn’t just about drying the surface—it lets the skins thicken, which seals in moisture and keeps out rot. A well-cured potato stored in a cool, dark place can last for months. Without curing, even healthy potatoes can spoil in storage within weeks.

Time of Day Makes a Difference

If possible, harvest in the morning after the dew has dried but before the heat of the day. This keeps the tubers cool and firm and reduces the risk of damage. Never leave freshly dug potatoes in the sun for too long—sunlight can turn them green, which makes them toxic due to solanine buildup.

Avoid Green Potatoes

Any potato exposed to light—whether above ground or left in the sun—can turn green. These should not be eaten. Always discard green potatoes or cut away any green parts before cooking. To prevent this, cover any exposed tubers in the ground with soil and store harvested potatoes in complete darkness.

Potatoes in Containers or Grow Bags

Container-grown potatoes are usually easier to monitor and harvest. You can lift the whole plant or gently feel around the edge for tubers and take what you need. These setups also allow better drainage, which reduces the chance of rot, but the soil may dry out faster—so check moisture levels regularly.

Successive Harvesting Is Possible

With early varieties or container planting, you don’t have to harvest all at once. You can dig up a few at a time as needed, especially for smaller or new potatoes. Just be gentle to avoid disturbing the rest of the plant.

Rotation Planning Starts Now

After you harvest, the soil is tired of potatoes. This is the time to start planning your crop rotation. Don’t replant spuds in the same bed next year—rotate with legumes or leafy crops to avoid pests like wireworm or diseases like potato blight.