The humble potato. The world’s favourite root vegetable. Boiled, mashed, baked, boiled, fried or roasted – nothing beats the taste of a fresh, ripe, well-seasoned potato, fresh out of the ground and cooked to perfection. Hash browns, chips, potato cakes or pie filling – potatoes are not only versatile but nutritious, inexpensive and, if you fancy growing your own, they’re relatively easy to plant and harvest.
Potatoes are classified as being either earlies or maincrops. Earlies (new potatoes) are ready to harvest much sooner than maincrops. Maincrops are in the ground a lot longer than earlies, producing a better yield and bigger potatoes, however, earlies are said to be much tastier!
Only got 5 minutes
One of the questions asked by first-time potato growers is “When will my potatoes be ready to harvest?”
Potatoes certainly aren’t the easiest vegetable to harvest as you can’t actually see them but what you can see are the flowers and these are your “eyes”.
There are three types of potatoes which can be grown during a typical growing season:
- First earlies
- Second earlies
- Maincrop
| Potato type | When to harvest | What you’re waiting for | Post-harvest |
| First earlies | June – July | Wait for the flowers to open or the buds to drop; wait for 14-21 days until the tubers are the size of hen’s eggs | Avoid curing and eat within 2-4 days of harvest – they won’t keep for much longer. |
| Second earlies | July – August | ||
| Maincrops | Late August – October | Wait until the foliage turns has died and turned yellow; then cut it and remove. Wait for a further 10-14 days before harvesting to allow the potatoes to develop a thick enough skin. Usually ready to harvest mid-September. | Allow them to dry for 1-2 hours before storing |
Planning the perfect potato harvest
- Check the weather and plan your harvest for a dry day.
- Dig slowly and with care – using a garden fork, not a spade – to avoid penetrating or bruising the potato skin.
- If the soil’s wet, allow the potatoes to air-dry before packaging or putting them into storage.
- If you’re blessed with a sunny harvest day, don’t leave freshly harvested potatoes out in the sun as they’re likely to turn green. Green potatoes, if eaten, can cause sickness and diarrhoea.
How to harvest
Earlies
- Gently remove the potato plant from the ground with either your hands or a handheld multi-pronged garden fork.
- Take as many tubers as you need and that are ready to harvest.
- Set the plant back in place in the ground.
- Pat down the soil so that the plant is securely back in place.
Maincrop
- Work from the edge of the planting row, gradually working your way into the centre using a spading fork.
- Insert your fork 10 to 18 inches away from the plant stem.
- Loosen and turn over the soil carefully with your fork, trying to avoid direct contact with the tubers. (Most of the tubers will be on the same level in the soil – around 4 to 6 inches below the surface).
- Gather the tubers by hand.
Potato types explained
Earlies
First and second earlies are commonly referred to as ‘new potatoes’. Despite the fact that they spend less time in the ground and so are smaller than maincrop, they typically have more flavour and taste better.
First Earlies
- Plant between mid-March and mid-April
- Growing time around 10-12 weeks
- Harvest time: early June/July
Second Earlies
- Planting second earlies is a good way of extending the new potato crop for a few more weeks
- Plant around late April
- Growing time around 10-12 weeks
Maincrop
- Plant during April.
- Growing time 15-20 weeks
- Harvest time from around mid-September until the first sign of frost
Top 5 Maincrop Harvesting Tips:
- Don’t wait too long after cutting the flowers of maincrop potatoes (i.e. longer than 14 days) before harvesting, otherwise, you run the risk of the tubers rotting.
- Before harvest, toughen up maincrop potatoes ready for storage by reducing their access to water after mid-August.
- Dig up a couple of ‘test’ potatoes from the maincrop to see how close they are to be ready for harvest – the skins of maincrop spuds should be fairly thick and attached firmly to the flesh of the potato. If the skin is thin and can be easily rubbed off, your potatoes aren’t quite ready and need a few more days in the soil before harvest.
- Potatoes do not respond well to cold conditions. At a push, they can handle a light frost but, when you check the weather and see the temperature is due to fall and there’s some serious frost on the way, it’s time to get your potatoes out of the ground!
- Allow freshly dug maincrop potatoes to rest in a dry, cool (around 7–15°C), well ventilated, dark environment with high humidity* for up to 14 days. In this time, their skins will cure and, as a result, they’ll have a longer shelf life – up to a month in some cases.
*Potatoes are around 80% water, depending on the variety, so high storage humidity is strongly advised to prevent shriveling.
Frequently Asked Questions
Can you eat green potatoes?
Never eat potatoes with excessive greening. Exposure to light causes potatoes to turn green due to the production of chlorophyll. The chlorophyll itself isn’t a problem but the same conditions that cause the potato to produce chlorophyll, also cause it to produce the natural alkaloid toxin, solanine.
Although a small amount of solanine is likely to be harmless, consuming a decent amount will cause illness – moderate to severe stomach pains, vomiting, and diarrhoea.
How long can you leave potatoes in the ground?
As a general rule of thumb, earlies should be harvested 10-12 weeks after planting however you can leave them in the ground for a further 2-3 weeks if you’d rather not lift them all at the same time. Just be aware that if they’re left in the ground too long, their skins will begin to harden and thicken and they’ll lose that delicious ‘new potato’ taste.
Maincrop potatoes are usually harvested in September but again they can be left; you can wait until November to lift them – as long as they’re out the ground before the first frost hits, you’ll still get a decent crop.
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