How to Tell if a Potato Is Bad?

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The humble potato is a staple food in many parts of the world. A member of the nightshade family, the potato comes in many varieties, including Yukon gold, russet, red, white, fingerling, yellow, purple, Elba, and Kennebec.

This versatile tuber is used in many recipes, so it comes as no surprise that most households have potatoes stored in the pantry or root cellar. Although potatoes keep a long time when properly stored, you might be wondering what are the signs that a potato is bad.

So, how to tell if a potato is bad? A raw potato should be firm to the touch without having any black spots, wrinkles, or bruises on the skin. Potatoes have gone bad if they become soft and mushy to the touch. A spoiled potato will also have wrinkled skin and a foul, moldy smell. Throw away spoiled potatoes to avoid food poisoning.

This article will explain how to tell if a potato is bad. Keep reading to learn how long potatoes last, what happens if you eat bad potatoes, and how to make potatoes last longer. 

Signs that Potatoes Have Gone Bad

Potatoes can stay fresh for a long time, but they can also go bad when not stored properly. Here’s how to tell if raw potatoes and cooked potatoes are bad:

Raw Potatoes

Uncooked potatoes have a long shelf life when stored properly. Raw potato is firm to the touch and has tight skin that’s void of any black spots, bruises, or blemishes.

One of the signs that a potato has gone bad is if it feels soft and mushy to the touch. This is also true for sweet potatoes which are high in moisture and become soft quickly once they go bad. 

A fresh potato has tight and firm skin. Spoiled potatoes have wrinkled skin and may also have black spots.

While raw potatoes have an earthy and nutty smell, they don’t smell bad. A musty and moldy odor is a sure sign a potato has gone bad. 

Cooked Potatoes

It’s usually harder to tell when cooked potatoes have gone bad, except for mashed potatoes. Mashed potatoes have gone bad when the liquid starts to separate from the solids. 

Sometimes cooked potatoes develop mold and have a sour and rotten smell. However, in some cases, cooked potatoes may contain harmful bacteria without any telltale signs. 

It’s best to eat cooked potatoes within four days of cooking and to always reheat them to eliminate any bacteria that may have developed. 

Sprouted Potatoes

Sprouted potatoes aren’t bad, but they can become spoiled or rotten in a couple of days. If you have a sprouted potato that doesn’t show other signs of spoilage, use a knife to peel or cut the sprout off and then prepare the potato in any way you see fit.

As the sprouts grow, they take the nutrients out of the potato. If the sprouts are very large, the potato likely has little to no nutritional value, and you’d be better off throwing it away. 

Sprouted potatoes are high in glycoalkaloids, which can be toxic when consumed in large amounts. Removing the sprouts, potato eyes, and green skin as well as peeling and frying may reduce glycoalkaloids levels in potatoes. 

How Long Until a Potato Goes Bad?

How long will potatoes stay fresh depends on several factors, including whether they are cooked and the way they are stored. 

Fresh potatoes generally last anywhere from one week to several months. Storing potatoes in a dark, dry, and cool place, such as a pantry or a root cellar helps them last longer than when stored at room temperature. 

The shelf life of cooked potatoes is shorter. Once cooked, potatoes can stay fresh for up to four days in the refrigerator or around one year in the freezer. Keep in mind that freezing lowers the quality of mashed potatoes. 

What Happens if You Eat Bad Potatoes?

Eating spoiled cooked potatoes may cause food poisoning. After just a few days in the fridge, cooked potatoes may become a breeding ground for pathogens and bacteria that could cause diseases like salmonella, botulism, listeria, and food poisoning. 

Eating spoiled potatoes can cause the following symptoms:

  • Nausea
  • Vomiting
  • Diarrhea
  • Stomach cramps
  • Fever
  • Muscle ache

Severe cases of food poisoning can lead to dehydration and may require hospitalization. 

To prevent this from happening, throw away any cooked potatoes that have been prepared four or more days ago. 

Tips on Making Your Potatoes Last Longer

Knowing how to store potatoes properly will increase their shelf life. Here are several tips on how to make potatoes last longer:

1. Store Raw Potatoes in a Breathable Container

Uncooked potatoes are best stored in a container such as a basket, box, or perforated bag that allows the air to circulate around the potatoes. Never keep raw potatoes in a sealed bag or an airtight container.

2. Keep Uncooked Potatoes in a Cool, Dry Place

Store fresh potatoes in a cool, dry, dark place, like a pantry, basement, root cellar, or cabinet that’s not in direct sunlight. Don’t keep fresh potatoes in the fridge, because cold temperatures can change the potatoes’ flavor, making them sweeter.

3. Keep Peeled Potatoes in the Water

Once the skin is peeled off potatoes, they will quickly change color. To prevent the peeled potato from turning brown, transfer it to a bowl and soak it in water. Don’t leave the potatoes in the water for more than 24 hours, otherwise, they will lose all essential nutrients.

4. Store Cooked Potatoes in an Airtight Container

Use a sealable bag or a lidded container to keep cooked potatoes inside. Keeping the air out of the container will increase the shelf life of cooked potatoes. 


Fresh potatoes can last for several months when stored in a dry, dark, and cool place. Cooked potatoes have a much shorter shelf life than raw potatoes and last up to four days in the fridge.

Throw any uncooked potatoes that feel soft and mushy and have a rotten or moldy odor. In the case of cooked potatoes, a strong sour smell and visible mold are clear signs of spoilage.

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