Mold On Potatoes – Signs ,Causes & Safety of Moldy Potatoes

Given how versatile potatoes are, it’s important to be aware of several items. How long should you keep them, where should you put them and how do you know when they’ve gone bad?

Over time they can go rotten and develop mold. Where you store them in addition to many other factors contribute to whether potatoes will get moldy and how long they last.

This guide will provide you with all the information you need to know about these issues and help you determine how to identify mold on potatoes.

Common Causes of Mold on Potatoes

There are a number of ways potatoes can get moldy. A very common one is not being stored at the right temperature.

They should be kept in a cool place, around 50 degrees Fahrenheit. This also will allow them to last longer.

The best places to store include the basement, away from areas that get sun or a cupboard since it is darker inside.

Indications of mold on potatoes include:

  • Softness or wrinkles
  • Exposure to moisture or wetness
  • Bad smell after cooking
  • Blemishes
  • Divots on the outside

Potatoes are 80% water and therefore can be susceptible to mold. The substance can start to appear in 1-2 days.

Washing off the dirt right away can lead to mold too. The best practice is to wait until you are ready to cook with them.

Sometimes the mold-forming process can start long before the potato is in your hand.

Early blight is a condition that occurs when the potato is still growing. Dark spots form and this can cause disfiguration as well as a softening of the vegetable.

It worsens when in storage, so by the time you get a potato like this, the chances of mold forming increase.

Signs Of Mold On Potatoes

One sure sign of mold on potatoes is smell. A musty or mildew-type smell indicates mold and you should throw out that potato.

Contrast this with the typical soil-like smell fresh potatoes have and you should be able to tell the difference.

Other signs include:

Small Patches Or Spots That Are Brown, Black, Red Or White

These can be problematic and mean the potato is starting to get unhealthy. The spots develop from small holes in the potatoes called lenticles through which they breathe.

Too much water or moisture causes discoloration when the lenticles swell up and these colored spots appear.

You can remove by peeling or cutting them. The potato is still safe to eat.

If the spots are all over, you should throw it out. Also, the more spots there are, the more chance of the potato tasting off.


This is an indication that your potatoes are about to spoil. However they are still safe to eat as long as you remove the sprout by breaking it off or cutting it.

Do not eat the sprouts. They contain toxic chemicals and consuming them can lead to neurological problems, digestive issues, headaches or vomiting.

Additionally, once a potato develops sprouts it is best to eat right away because they will suck out the nutrients and sugars. This causes the vegetable to shrink, become soft and that can lead to mold forming.

When looking at which potatoes to choose, find ones that are hard, look healthy and don’t have too many rings or damage. These types will last the longest and be more resistant to growing sprouts.

Potatoes sprout when the temperature is about 68 degrees Fahrenheit. If you don’t have a cool, dark place to keep them, you can put them in a brown paper bag, as this will reduce how quickly sprouts develop.

Another item to watch out for is green spots. This is a sign that a toxin has gotten into the potato.

You should immediately throw out any potatoes that are green. Eating them can cause stomach or neurological problems.

One way potatoes get green is if they are exposed to too much sunlight, so keep that in mind when choosing where to place them.

For cooked potatoes, it can be tougher to spot mold. If there is a bad smell coming from what you cook, this is an indication of mold.

If any liquid comes out and separates from the solid, this is another sign of mold on cooked potatoes. This can happen particularly with mashed potatoes.

Mold on cooked potatoes should be thrown out. Do not cut away the moldy part and eat the rest.

What Happens If You Eat Moldy Potatoes

In general, eating moldy potatoes won’t do much harm. But the food won’t taste good and you’ll have a brief reaction to it.

With that said, it’s never good or smart to eat any moldy food so avoid doing so.

If you do consume a moldy potato, you could develop food poisoning, fever, nausea or stomach cramps. While rare, you might need to be hospitalized.

Additionally, potatoes are the most common cause of solanine poisoning. Solanine is the toxin that develops from the aforementioned green color that potatoes sometimes get.

Eating this can cause the following:

  • Vomiting
  • Diarrhea
  • Headache
  • Paralysis of central nervous system

When might this occur? This depends on how many green potatoes you’ve eaten and your weight.

Someone who weighs a lot would need to eat a large amount while someone who weighs less could experience these symptoms from having a small amount.

The best thing to do is avoid eating green potatoes altogether.

How To Prevent Potatoes From Getting Moldy

A big part of keeping potatoes from mold is storing them properly. There are several ways to do this and many tips to keep in mind.

  • Store in a dark, cool place that has good ventilation
  • Place in bags with holes
  • Avoid areas that are high in temperature or get lots of sunlight
  • Don’t wash them before storing. This can cause them to spoil sooner.
  • Avoid storing in the fridge. This will cause the potato starch to turn into sugar which will have an effect on taste and texture.
  • Ideal temperature is between 45-50 degrees Fahrenheit

Spreading out the potatoes so they are not touching each other will increase their longevity, too. Don’t put them near other fruits or vegetables because this will cause premature ripening and a transfer of flavors.

It’s especially important to keep them away from onions. Each releases a gas that will cause the other to ripen.

For those who grow their own potatoes, be aware of sprouting. This can easily happen if they are not stored properly.

Unlike store-bought ones which are sprayed with chemicals to prevent sprouting, home-grown ones can develop sprouts quickly.

Once you cook any potatoes, they should be eaten in 4-5 days. Any longer than that and mold can easily develop.

Store cooked potatoes in a sealed container in the fridge.

Another method is to keep them in your freezer. You should boil them first and then place them in ice water.

Cutting them into pieces before freezing is best, too. Place in a closed container or vacuum-sealed bag and they can last about 10 months.

How Long Do Potatoes Last?

If stored right, potatoes can last a long time. Kept at room temperature, potatoes can last about 4 weeks.

While it is not recommended, if you store them in the fridge, potatoes will last a few months.

Keeping them in a cold area of the home like the basement will increase their lifespan, and those should be good for about 4 months.

While there is some slight variation based on what kind of potatoes, this information applies to all types.

A good way to tell if the potato starts to go bad is when it is soft to the touch and no longer has that firmness.

What To Do If You Find Mold On Potatoes

If you find mold on potatoes, you don’t necessarily need to throw it out. This depends on how much mold is on it.

If the mold is contained to a small area, cut that part off and discard. The rest of the potato can be eaten.

Should the mold be found throughout the potato, then it is spoiled and you should throw it out. This goes for raw potatoes.

If you find mold on cooked potatoes, do not eat and discard immediately.

Remember for the most part, you most likely won’t get a serious illness if you happen to eat a moldy potato. But this doesn’t mean you should purposely consume one.

Symptoms can develop.

Be safe, smart and when in doubt, throw it out!

Sometimes you can see whether a potato is bad before buying, cooking or eating one. For example if the skin is wrinkly or has a lot of spots, this is one you should avoid.

You also can cut a small piece of the potato open to see if there is mold on the inside.

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