How to Tell When Potatoes Are Ready to Harvest

Illustration of potato grow bags and a basket of harvested vegetables

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Determining when potatoes are ready to harvest depends primarily on the variety you have planted—whether they are first earlies, second earlies, or maincrops—and how you intend to use them. For early varieties, the key indicators are the flowering of the plant and the size of the tubers. For maincrop varieties, the signal is typically the yellowing and dying back of the foliage. Because the crop is hidden underground, the most reliable method for any variety is to gently scoop away some soil to check the tuber size before committing to a full harvest.

Table of Contents

Identifying early potato readiness

Early potatoes, which include both first and second early varieties, are grown as ‘new potatoes’. These are harvested while they are still small and have thin skins, making them ideal for immediate consumption.

Visual cues for earlies

Flowers opening or buds dropping can be a useful cue, but some varieties flower little or not at all. Check the variety’s expected maturity and sample a tuber; a hen’s-egg size is a useful guide for new potatoes. Depending on the specific variety and local weather conditions, these windows typically fall as follows:

First earlies: Generally ready to lift between June and July.
Second earlies: Generally ready to lift between July and August.

The ‘sample and cover’ method

Since flowering is not a dependable test for every variety, use a trowel to carefully remove a small amount of soil from around the base of a few plants. If the tubers have reached the desired size, you can begin harvesting. If they appear too small, simply cover them back up with soil; the plant will continue to develop the tubers.

Determining maincrop potato maturity

Maincrop potatoes are grown for larger tubers suitable for roasting, baking, and long-term winter storage. They remain in the ground significantly longer than early varieties, typically from late August through to October.

Signs for immediate use

If you intend to eat your maincrop potatoes fresh, you can start lifting them in late summer. Like earlies, you can use the sampling method to ensure they have reached a satisfactory size for your culinary needs.

Signs for winter storage

To ensure maincrop potatoes are suitable for storage, they must be allowed to ‘bulk up’ and develop a thicker skin. The primary indicator for storage readiness is when the foliage turns yellow and begins to die back. Once the leaves have yellowed, the following steps are recommended to ensure the tubers do not rot during winter:

Cut off and remove all top growth.
Leave the tubers in the ground for approximately 10 days to allow the skins to harden.
Dig up the tubers and leave them in the sun for a few hours to dry.
Brush off any remaining soil before storing.

Harvesting indicators for container-grown potatoes

Potatoes grown in bags, sacks, or pots follow similar biological timelines to those in the ground, but they offer a more direct way to monitor progress.

Watering and foliage signals

Do not stop watering a still-growing crop to create a harvest signal. Drought can kill foliage before tubers mature. Use the variety, elapsed growing time and a sample tuber; natural dieback is most useful for mature maincrops.

The advantage of containers

Unlike ground-grown crops, container potatoes can be harvested without the risk of spearing the tubers with a fork. The most efficient method is to gently tip the entire contents of the bag or pot onto a flat surface and pick the potatoes out by hand.

Diagnosis of tuber health during harvest

When lifting potatoes, it is essential to diagnose the quality of the tubers to ensure safety and storage viability.

Identifying poisonous tubers

During the harvest, you may find potatoes with green skin. This occurs if the tubers were exposed to light, often due to insufficient earthing up. Green potatoes contain solanine and are potentially poisonous; these must be discarded and not consumed.

Assessing storage suitability

Not every potato harvested from a maincrop is suitable for the cellar. Only store tubers that are undamaged. Discard rotten or green tubers. Sound potatoes with minor harvest damage can be used promptly, but should not join the storage crop.

Techniques for lifting without damage

The method used to harvest can affect the quality of the crop, particularly for maincrops intended for storage.

Ground harvesting

To avoid damaging the tubers, insert a garden fork at least 30cm away from the base of the plant. This distance reduces the likelihood of spearing the potatoes. If you only require a small amount of potatoes for a single meal, you can use a trowel to carefully dig beside the plant and remove a few tubers without disturbing the root system, allowing the plant to continue growing.

Post-harvest curing

For maincrops, curing is a vital step. After lifting on a dry day, leave the potatoes on the soil for approximately two hours. This dries surface moisture before storage; it does not eliminate rot risk. Move potatoes into dark storage after drying and check stored tubers regularly.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Garden fork: Used to lift potatoes from the ground while minimising damage to the tubers. Ensure the tines are sturdy and the handle is ergonomic for lifting heavy soil. Search Amazon for Garden fork.
Hessian sacks: Necessary for storing maincrop potatoes in a cool, dark, frost-free place. Check for breathable material to prevent moisture build-up and rot. Search Amazon for Hessian sacks.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.