How to Tell When Your Potatoes Are Ready to Harvest

It’s easy to tell when certain crops are ready to harvest, but what about potatoes? These tasty tubers are buried beneath the earth throughout the growing season, making it difficult to determine when to dig them up.

Fortunately, potatoes provide a few clues that signal it’s time to start harvesting. Ahead, our experts explain all the signs you should watch for. 

Flowering

Potato plants typically flower about 7 weeks after planting. Once this has occurred, wait another couple of weeks. During this time, the flowers will likely fall off, and you can then begin harvesting new potatoes.

However, keep in mind that these will be smaller than fully mature potatoes and have thinner skins, so they are not suitable for long-term storage.

Maturity Date

There are many different varieties of potatoes, and their window for harvesting varies widely. Some, like Norland, are early-season potatoes, some are mid-season (like Kennebec), and some are late-season.

“Keep track of when you planted and use the listed maturity date for each variety,” adds Travis Key, founder of Lazy Dog Farm. Then, keep an eye on the calendar, as well as any physical signs that your plant may be exhibiting. “If you leave the potatoes in the ground too long, they can rot, sprout, or start to form white spots,” he adds. 

Changes to Foliage

Foliage is the most noticeable and reliable sign. As the season progresses, the potato’s leaves will begin to turn yellow and brown; eventually, they will wilt and die.

“Your potato plants may look pretty pitiful as they approach their 90 to 120 day maturity date,” says Key. “But believe it or not, [they’re] still growing under the soil.”

The overall look of the foliage can guide you in harvesting. “Once the foliage begins to turn brown, watch for a few weeks until it’s completely dead and yellow,” says Austin. Waiting a few weeks after the plants die back lets the underground tubers develop thicker skins, which will be beneficial for long-term storage.

“If your soil conditions are favorable (not too wet), allow the plants to die completely to the ground before harvesting,” Key says. “This will ensure you get the largest potatoes possible.”

Thickening Skins

Unsure about whether your potatoes are mature? You can do a quick experiment by digging up a couple of tubers. Then, evaluate their skins: Are they still so thin that you can easily rub the skin away? Or are they developing thicker, tougher skins? The answer can help you determine whether to start harvesting.

Key suggests occasionally scratching the mound around the potatoes as they’re dying back. “This will also help give you an idea of whether they’re an acceptable size for harvesting,” he says. “Just be sure to cover [them] again with soil so they don’t turn green from sunlight exposure.”

How to Harvest Potatoes

Harvesting potatoes is a delicate process. It’s important to prevent them from being damaged so they have the best chance of success in long-term storage.

You can use a garden fork to carefully loosen the soil around the potato plants, but go slow, and try not to accidentally spear any. Dig deep and lift the potatoes up with the soil, then gather them up. Your plants may have produced more potatoes than you expect, so sift carefully—you don’t want to inadvertently miss any!

Keep an eye on the weather forecast during the harvesting period. “If you’re getting significant rainfall as your potato plants are dying back, consider an early harvest,” suggests Key. “Maturing potatoes can rot if the soil is too wet, so go ahead and harvest them to prevent that from happening. Smaller potatoes are better than rotten potatoes.” 

After harvesting, it’s important to remember the next step: curing. “Curing toughens up a potato’s skin and extends its storage life,” says Austin. She recommends placing the potatoes on newspaper in a cool, dark, well-ventilated place—about 50 to 60 degrees Fahrenheit.

“After about two weeks, the skins will have toughened up. Rub off any large clumps of dirt—potatoes should never be washed before storage—and cull any damaged tubers, which should be eaten, not stored,” she says.