When to harvest potatoes

You can do so much with potatoes, which makes them a favorite part of just about any meal. They are quite an easy crop to grow and will last through winter, if you harvest them at the right time.

The growing season of potatoes lasts 4-5 months, & harvested at the end of fall, after the first frost, when the foliage has died back. Potatoes can be left in the ground a few more weeks, so the skins will harden. Harvest potatoes by digging up gently, so that the skins are not damaged.

Read on to understand how long potatoes take to grow and when they are ready for harvesting.

When to harvest potatoes

Mature potatoes can be harvested at the end of the growing season, after the foliage has died. This means about 19 – 20 weeks after planting. They should be harvested when the soil is dry and before the temperatures drop to near 32 °F (0 °C).

New potatoes can be harvested as soon as two to three weeks after the plants stop flowering.

This means they are viable as a crop after about seventy days.

More mature potatoes can be harvested a few weeks after the foliage has died.

Potatoes can survive a light frost, but need to be harvested before the temperatures drop too low.

Definitely make sure you get the potatoes out of the ground before it approaches freezing.

You should also harvest potatoes when the weather is dry.

Too much water in the soil can make it compact, which means the potatoes will not come out easily.

How to know when potatoes are ready to harvest

Telling when potatoes are ready to harvest depends on the foliage of the plant. Once it has flowered, new potatoes are ready to harvest after 2 – 4 weeks. Mature potatoes will be ready to be harvested 3 – 4 weeks after all the foliage has died back.

The key to knowing when potatoes are ready to harvest is the plant’s foliage.

When the potato plant flowers, it is a signal that the tubers are beginning to mature.

If you are looking for small, new potatoes, you can harvest them two to three weeks after this.

For larger potatoes, you will need to wait for the flowers and leaves to die.

When all the foliage has died back, the tubers will stop growing and can be harvested.

You can leave the potatoes in the ground so that the skins can mature and harden.

If you want to make sure that the potatoes are ready for harvesting, do a test.

Dig up a few potatoes and feel the skins.

If they are thin, then leave the tubers in the ground for a few weeks.

When are potatoes ready to harvest?

Potatoes are ready to be harvested about 4 – 5 months after planting. This is when the plants have flowered and then the green part has died back. However, if the foliage does not all die, it may be necessary to cut the top of the plant off.

Potatoes usually reach maturity between four and five months after planting.

After the plants have flowered, the tubers can be harvested, but will be very small.

When the foliage dies back, the potatoes will be ready to harvest.

This is usually about eighteen to twenty weeks after planting.

As long as the part of the potato plant above the ground is alive, the tubers will keep on growing underground.

Often, the green part of the plant will not die completely, which means the tubers may continue growing.

If this happens, the tops should be cut off the plants, so the skins of the tubers underground can mature and harden to be suitable for storage.

When to harvest sweet potatoes

Sweet potatoes are very sensitive to frost, so they should be harvested no later than after the first fall frost. When the leaves turn yellow and the foliage starts dying, it is a sign that the tubers are ready to be harvested.

Sweet potatoes can be ready for harvesting between three and six months after planting.

This depends on the climate of the area they are being grown in.

Because sweet potatoes are very sensitive to frost, they must be harvested no later than just after the first frost in fall.

A sure sign that the sweet potatoes are ready for harvesting is when the leaves of the plants have turned yellow.

This means that the tubers have matured and stopped growing.

See our tips on how to grow sweet potatoes.

How long do potatoes take to grow?

From the time of planting, potatoes take 90 – 120 days to harvest, depending on the variety. For small potatoes, harvesting can be done in 60 – 70 days. New potatoes are typically ready to harvest 7- 8 weeks after planting.

Young or new potatoes can be harvested as early as two weeks after the plants flower, which gives them a shorter growing period.

Potatoes are grown from pieces of a tuber, or from small potatoes.

These seed potatoes can begin to sprout between two and four weeks after planting.

The plants will flower about seven to nine weeks after planting.

This means you can expect to see the flowers anywhere from five to seven weeks after sprouting.

New potatoes can be harvested as soon as two or three weeks after the plants stop flowering.

The more mature, larger potatoes can be harvested two to three weeks after the flowers and leaves die.

This is usually about eighteen to twenty weeks after planting.

See our tips for growing baby potatoes.

How to harvest potatoes

To harvest potatoes, wait until the foliage has died–usually after the first frost–then gently loosen the soil with a shovel, garden fork, trowel, or even by hand. This will allow you to lift up the entire plant without damaging the potatoes.

Harvesting potatoes means digging them up.

However, you don’t want to damage the tubers when you do so.

Use the plant above the ground as a guide when you harvest.

The potatoes underground shouldn’t cover an area that is wider than the spread of the leaves and stems.

Provided the seed potatoes were planted about two feet apart, there should be a gap between the tubers of one plant and those of the next.

The roots of the potatoes can grow up to 18 inches deep, so you will need to dig to at least this depth to get all of the tubers.

To dig them up, use a shovel and garden fork.

Loosen the soil around the spread of the plant.

Then, gently loosen the soil closer to the stem, taking care not to damage any tubers underground.

You may be able to lift the whole plant, tubers and all.

It is more likely you will have to dig them up, so do so gently.

Find out how deep you should plant potatoes.

Conclusion

Potatoes have quite a long growing period over summer. 

They are susceptible to frost, so they must be harvested before the temperatures fall. 

The best indicator of when to harvest potatoes is the foliage: when it is dead, the potatoes stop growing and can be harvested.

About the author

Greg Volente

Greg Volente holds a Naturalist Certificate from the Morton Arboretum, worked for The Nature Conservancy leading environmental education programs and doing natural areas restoration, and worked in the soil science research & testing lab at Michigan State University. Besides gardening, he's an avid wildflower enthusiast, and loves botanizing, hiking, and backpacking.

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