washing a potato under a tap with running water

Should You Wash Potatoes Before Storing Them?

Growing your own potatoes in the home garden and storing them for winter use is a great way to provide your family with healthy, nutritious food. Knowing when to harvest them and get them ready for storage is important too. Find out what the experts have to say about harvesting, washing, and storing potatoes for the winter.

Should you wash potatoes before storing them?

In normal circumstances, potatoes do not need to be washed before storing them. The soil will not stick to the tubers when you harvest in dry conditions. Harvesting when the soil is dry prevents wet soil from sticking to the potatoes which will prevent issues with spoiling during storage. However, sometimes, washing your newly harvested potatoes may be beneficial if they are covered in sticky wet clay soil says the Oregon State University Extension Services (OSU).

Potatoes grown in heavy clay soils may be covered with sticky soil when harvested. In this case, washing the potatoes to remove the soil may be necessary. The key to success with storing potatoes that have been washed after harvesting is to dry them thoroughly before putting them into storage.

Why should potatoes be harvested in dry soil conditions?

Potatoes harvested when the soil is dry are less likely to have issues with spoilage during storage. Dry soil falls off the tubers easily, leaving the potatoes clean and dry. It is best to stop watering your potatoes after the foliage has yellowed and died back, and the tubers are mature.

potatoes on a roller table sorting equipment
Excess dry soil easily falls off potatoes on sorting equipment.

What should I do if I harvest my potatoes with wet soil on them?

Sometimes harvesting your potatoes when the soil is wet is unavoidable, especially if you get a rainy spell at harvest time. With sandy soil, the solution is simply to let the potato tubers dry in a cool, dark area before moving them to their permanent storage place.

Potatoes grown in soil with high clay content take a little more work as the soil may be sticky and cling to the potatoes. In this case, washing the potatoes may be necessary before storing them.

Use your garden hose to wash away sticky soil that clings to your potato tubers. Put the tubers on a tray or in a newspaper-lined bin and place them in a cool, dark, well-ventilated area to dry. If possible, spread the potatoes out, allowing space between the individual tubers. It is vital the potatoes are dry before storing them. Moisture encourages spoilage.

When should you stop watering potatoes?

Stop watering your potatoes when the foliage yellows and begins to die back. Your potato tops may flop or sprawl over the soil. This lets you know the potato plants have matured and are ready for harvest. The plants no longer need water as they have stopped growing and have ended their growth cycle. Potato tubers have stopped growing, too, and don’t need water.

OSU recommends reducing the water to your potatoes by mid-August to help toughen the skins and prepare them for winter storage.

How do you know when potatoes are mature and ready for harvest?

The tops of potato plants die back naturally when they have finished growing, and the tubers are mature. Foliage turns yellow and may flop to the ground as it turns brown and dies. Dying potato foliage is part of the natural growth process. You should let the tops die back entirely before harvesting potatoes for storage.

Mature potato tubers have tough skins to protect them. The potato is still immature if the tubers have thin skins that can be scraped off easily with your fingernail. If your potato plants have died back, but the tubers still have thin skins, leave them in the soil for another week and recheck them.

Do you need to cure potatoes before storing them?

Curing your potato tubers gets them ready for long-term storage. Place them in a dark, well-ventilated area with high humidity and average temperature for ten days. Curing also gives any nicks and bruises on the tubers time to heal before you store them. OSU Extension Services explains that potatoes that have been cured will last longer in winter storage.

massive ventilation fans in a potato store
Massive ventilation is a necessity in large potato stores

Where is the best place to store potatoes?

Nearly everyone knows that potatoes need to be stored in a cool, dark area, but many are surprised to learn they need moderate to high humidity, too.

Humidity: Because potatoes are approximately 80 percent water, storing them in excessively dry areas runs the risk of the potatoes losing too much moisture and shriveling. Potatoes need some moisture to keep them firm and fresh. Choose a location with moderate to high humidity.

Darkness: Light is also an issue with stored potatoes. They must be stored away from both sunlight and artificial light. Light causes the potatoes to turn green, a sign of high levels of chlorophyll and the toxic alkaloid solanine in the skin. Green potatoes are not edible. Light exposure also encourages potatoes to sprout in storage.

Temperature: Potatoes need to be stored in a cool area where temperatures remain above freezing. Recommendations for the ideal temperature for storing potatoes vary from 35 to 45 degrees. Harvest to Table recommends keeping them at temperatures between 35 and 40 degrees, while OSU says 40 to 45 degrees is best.

Keep in mind that potatoes chill easily. Chilled potatoes become sweet as it causes sugars to build up in the tubers. Although they are still safe to eat, many do not like the change in flavor.

Choose an area with consistent temperatures that is not susceptible to a sudden drop near freezing in the winter to avoid chilling the potatoes. Temperatures that are too high will cause potatoes to sprout. A consistent, cool temperature is essential for keeping your potato tubers firm and tasty during winter storage.

Ventilation: Potatoes need adequate air circulation during storage to prevent spoilage. You can store your potatoes in open bins, on screened trays, or in paper or burlap bags to help increase ventilation.

A good place to store potatoes would be an underground cellar or vegetable store as they are cool, slightly damp, have some ventilation, are dark, and are free from frost all year round.

How long will potatoes keep in storage?

The storage length of potatoes depends on proper storage conditions, but there are other variables, too. Some varieties of potatoes stay fresh in storage longer than others. OSU recommends growing late-maturing potatoes as they tend to keep longer in storage.

The maturity of the potatoes affects their storage life, too. Fully mature potatoes may be stored for nine months, while immature/ new potatoes will only last a few weeks.

Summary

As a rule, it is best to avoid washing your potatoes when you harvest them, as wet potatoes do not store well. However, there are times when washing your potatoes may be necessary, especially if they have been grown in soil with high clay content. But don’t worry, as long as you dry your potatoes thoroughly before putting them in storage, most will do just fine.