a pile of rotting bad potatoes

How To Tell If A Potato Is Bad

The purpose of this article is to teach you the skills required to make a quick assessment about how to tell if a potato is bad or not just by looking at it.

There are a variety of factors that determine the shelf life of potatoes. It depends on the type of potato, how the potatoes were stored, and the humidity of your climate.

How to tell if a potato is bad

The easiest way to identify a bad potato is by looking at the color of its skin. If a potato is old but healthy, its skin will not discolor, it will feel soft and its skin will be wrinkly. This is normal as old potatoes eventually dehydrate through respiration. However, if a potato is infected with a disease, either a small area or the whole of the potato will discolor to a dark color, it may have mold or white fungal spots too, and soon the whole potato will turn into a rotting mush with a foul smell.

How long do potatoes last?

Most potatoes can last about 3-5 weeks in the cupboard, and 3-4 months in the fridge. Potatoes are one of the most popular foods in the world due to their relatively low cost and proven health benefits. They can be cooked in many different ways.

Once you’ve bought your potatoes from the store, store them properly at home. The shelf life of potatoes past their sell-by date is as shown in the table below.

Potato VarietyCupboard/PantryFridgeFreezer
 Storage timeStorage timeStorage time
Russett or white potatoes3-5 weeks3-4 months
Yukon gold potatoes2-3 weeks2-3 months
Red or new potatoes2-3 weeks2-3 months
Fingerlings2-3 weeks2-3 months
Sweet potatoes3-5 weeks2-3 months
Slice potatoes or french fries1-2 days6-8 months
Cooked potatoes5-7 days6-8 months
Baked potatoes5-7 days6-8 months
Mashed potato4-6 days6-8 months
Instant dry potato packages1 year4-5 days
Recommended storage times for potatoes

The temperature and humidity of where you store them in your home should also be taken into consideration.

Potatoes are fresh when picked and will keep in good condition for months in a cool dry environment. But if they’re kept for too long in a warm, humid environment, they will eventually begin to form spouts. Or if the potatoes have been damaged they will begin to rot.

The sprouts can be cut off and the potato can still be used for eating, but the quality will be diminished. It is possible to plant the potato with sprouts on to grow your own potatoes.

You will also notice green spots if the potatoes are exposed to direct sunlight for longer than recommended. In which case, the green spots can be cut off while the rest of the potato can be used.

Moisture and potatoes

When potatoes are stored wet, they can form a mold around them. If this happens, then they need to be thrown out. So, be mindful not to wash them before storage.

There are health risks involved with eating spoiled foods, so remember to be aware and enjoy your food before the shelf life expires.

You might not notice that your potato has gone bad until you get to the middle, as it might have blemishes or bad spots on the inside that you’re unable to identify from the outside.

If you notice any dark spots, unusual color or strong smell coming from inside a healthy-looking potato, this is a huge warning sign that it has gone bad.

Storing potatoes to extend their shelf life

Potatoes are best stored in a dark, cool place, such as a cellar. They can remain in this state for several months, as long as the temperature is 45-50 degrees Fahrenheit.

If you keep them at a higher temperature, then there is a risk of shrinking and spouting, especially if the humidity is low. This is because potatoes are composed of 80% water, which evaporates in a hot, dry climate.

Once you’ve cut open a raw potato, they oxidize quickly. This can be eliminated temporarily by putting them into a pan of salted water directly as you cut them.

As potatoes are prepared, they should be stored in an airtight container to keep the moisture out, as well as other contaminants.

Raw potatoes don’t freeze and will turn to mush once defrosted. But potatoes that have been cooked – even partially such as french fries, can be stored for months.

What does a bad potato look like?

An easy way how to tell if a potato is bad is by its physical appearance. A bad potato has black spots, bruises, mould, wrinkly skin, and other blemishes. If this is the case with yours, you should throw it in the bin.

a bad rotten mouldy potato
Notice the skin discoloring to a dark color, plus the presence of mold, the inside of the potato will be mushy and smell terrible.

What does a bad potato feel like?

Good potatoes should be firm to the touch with tight shiny skin. If potatoes are soft, mushy, or wrinkled, then this is either rotten or very old and should be discarded.

What do bad potatoes smell like?

Healthy potatoes have a nutty or earthy smell. If they smell moldy or musty, then this is a good indicator of a bad potato. The smell which comes from a rotten, blighted potato is unbelievable. It is a strong sulfur smell.

If I ate a bad potato what would happen?

It is highly unlikely that you would ever eat a bad potato as it would have dark skin and dark flesh if it made it through the cooking. Most likely a bad potato would disintegrate in the pot.

I think the only time you would eat a bad potato is if it was sunburnt or green. Even then you would know it is off by the bad taste it would give in your mouth.

After all these signs if you continued to eat a bad potato you would have a slight headache, diarrhea and vomiting.

What should I do with a bad potato?

When only a small portion of the potato is affected by something like sunburn, then you can cut the bad parts off and use the rest. Although if the majority of the potato was green then you should throw it in the bin. If the potato is rotten or moldy anywhere it should be discarded.

Just because one potato is bad, this doesn’t mean the others will be affected too, so don’t worry too much if you come across one. The others in the bag should be ok.

If your potato is black or green, then this is past saving and you should throw it away.

What to do with sprouted potatoes

Your potatoes have ‘eyes’, and this is where the sprouts come from. They are small bumps or indentations where the tubers stem and sprout new plants.

Sprouts might look unappealing, but the potatoes are safe to eat as long as you remove the sprouts. All you have to do is snap them off with your fingers.

Do not eat the sprouts, they can be toxic and will make you sick.


To sum this article up, your average potato can last 2-4 weeks in the cupboard (depending on the temperature and humidity) or 3-5 months in the fridge.

If a potato is bad you will notice blemishes, green spots or black spots, or wrinkly skin. You will also notice it will smell really bad. They won’t smell earthy and nutty anymore but have a terrible sulfur smell.

The likelihood of you eating a bad potato is very low. Its physical appearance or smell and taste will ensure it will go no further than your mouth. When you come across a bad potato, throw it in the bin.