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How to Tell If a Sweet Potato Is Bad (4 Clear Signs + Tips to Make Them Last)

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Nobody in their right mind wants to smell or eat a rotten sweet potato. Yuck. And Pee-U! So we’re sharing how to tell if a sweet potato is bad or still good.

That is our mission here today. To learn when a sweet potato spoils and should not get eaten.

We’ll also look at how long it takes a sweet potato to turn, what you can do with spoilt sweet potatoes, and some nifty storage tips to make your sweet potatoes stay good as long as possible.

OK, ready?

Let’s jump straight into the action!

How to Tell If a Sweet Potato Is Bad

moldy sweet potato on a wooden table not good to eat
Sweet potatoes are highly perishable vegetables – with a ton of water content! But how to tell if a sweet potato goes bad? The best rule of thumb is to follow your senses! Look out for moldy white spots, pungent odors, and green fuzz. If your sweet potato looks and smells safe to eat, chances are it’s still good. But if you see a moldy mess, as in the image above, it’s time to chuck it into your compost bin! (And don’t worry. We’re about to share some of our best tips to ensure your sweet potato doesn’t spoil in the first place. You can avoid moldy sweet potatoes!)

Everyone knows how nutritious and delicious sweet potatoes are. My family eats them at least a couple of times every month, certainly not just at Thanksgiving, but then too!

Sweet potatoes have a long shelf life compared to many other foods. But they can spoil and become unfit for consumption if you don’t use them within the proper time frame.

So, you’re wondering how to tell if a sweet potato spoils.

Good news. It’s pretty easy!

Look for these four primary telltale signs.

  1. Typically fuzzy, white, black, or green mold
  2.  A funky smell that cries, Don’t eat me!”
  3.  A soft or mushy texture
  4.  Dark skin or spots

If you notice these signs on your sweet potatoes, it’s probably best not to eat them. Sweet potatoes should be firm, smell like earth, if anything, and not grow fuzzy mold!

Are Old Sweet Potatoes Safe to Eat?

farmer harvesting fresh sweet potatoes from the garden soil
We found a legendary document from the United States Department of Agriculture when researching sweet potato storage. It’s the Farmer’s Bulletin Issue Number 970 – Sweet Potato Storage! The information is dated, as it got published in May of 1918. However, as gardening geeks, we love old-school agricultural data like this! The guide contains several sweet potato-growing and storing insights – including ideal sweet potato storage conditions, humidity and temperature ranges, et cetera. It also shows how to build a sweet-potato storage house. From scratch!

Who in the heck doesn’t like sweet potato fries? I sure do! All crispy outside with a creamy texture within. Mmmmm.

However, if a sweet potato has black spots, brown spots, other dark spots, soft spots, or a mushy texture, you shouldn’t eat it.

Plus, it might not be safe to eat starchy root vegetables like sweet potatoes that you’ve had stored for a good while. And please, get rid of them if you notice the presence of mold!

Medical News Today reports that ripened sweet potatoes are excellent sources of beneficial dietary fiber, vitamins, minerals, and other phytonutrients, like carotenoids and antioxidants.

However, if a sweet potato passes its optimal ripeness and begins to spoil, it may no longer be safe for human consumption. That’s because a rotten sweet potato may develop potentially harmful contagions, like fuzzy mold, that can make people sick.

So, if you doubt whether one of these nutritious root vegetables is good or bad, it’s probably best to find a different use for it besides eating it. We’ll review some things to do with sweet potatoes that have gone south in just a minute.

But first, consider these sweet potato insights derived from years of root-crop gardening and learn how to tell if a sweet potato is bad!

Read More!

How Long Before a Sweet Potato Goes Bad?

raw sweet potatoes sliced on a wooden table ready for cooking
We’ve kept sweet potatoes fresh in our cellar on a wooden table for around six months without fuss. But you need to cure them first! You can store them at 55 to 60 degrees Fahrenheit after curing. But we read a fascinating warning on the University of California’s Post Harvest website. They remind us that if the long-term storage temperature far exceeds 60 degrees, the sweet potatoes may sprout! We also read from the Iowa State Extension that if you store sweet potatoes below 55 degrees, the flavor spoils, and the flesh may have an off-appearance. (Sweet potatoes are like Goldilocks. They need perfect temperature conditions for long-term storage. But if you meet those conditions – they keep safely for months.)

I’ve never met a sweet potato gardener who didn’t stress about how long their harvest lasts. How long does it take before a sweet potato goes bad? What is the accepted sweet potato shelf life?

Well, it turns out that the answer depends on several different factors, including the following.

  • How ripe the sweet potato was when you harvested or purchased it
  • The environmental conditions where you store your sweet potatoes
  • The method you use for storing your sweet potatoes
  • Whether or not you cured your sweet potato before storing it (curing is so critical!)

The riper a sweet potato is when you either harvest or buy it, the less shelf life it will have before it begins to turn.

The only way you can control this is if you’re growing your own because then, you determine the harvest time of the raw potatoes. If you buy your sweet potatoes, you will have no control over their maturity.

Sweet potatoes can last for several months if it gets stored properly. Otherwise, signs of mold may develop, and the texture might get off.

Light and heat will cause root vegetables like sweet potatoes (and regular potatoes) to rot and produce sprouts. Nobody wants that.

So, you should always store your sweet potatoes in a dark, cool place, like a root cellar or another type of dry pantry. That’s why we have root cellars!

However, if you don’t have a root cellar, consider storing your sweet potatoes in a cabinet, closet, or pantry – anywhere you can block out the light and keep it cool is ideal!

Below, we’ll look at several effective ways to store sweet potatoes. That way, they last as long as possible.

But first, consider the following.

Can You Still Eat Sweet Raw Potatoes That Have Sprouted?

sprouting sweet potatoes in a wooden bowl
Want to keep your sweet potato from spoiling? It all starts at harvest! We’ve read from several scholarly articles that sweet potatoes are tremendously susceptible to damage and bruising during harvest. If the sweet potatoes get damaged during this integral time – you can expect them to go bad much faster. No more sweet taste! But no worries. Curing your sweet potatoes for a week before storage increases their shelf-life and also helps reduce bruising. Curing is easy. Here’s our favorite sweet potato harvest guide from the Alabama A&M and Auburn University Extension that teaches how. They advise placing your sweet potatoes in a warm and moist location for four to seven days (roughly 80 to 86 degrees Fahrenheit). The humidity should stay in the 90 to 95 range. Curing also helps the sweet potato convert starch to sugar – resulting in a superior sweet taste.

Exposure to heat, light, and air can cause all sweet potato varieties to begin sprouting.

Is it safe to eat this starchy root crop with sprouts coming out of it? How can we tell if a sweet potato is bad when it has sprouts?

According to Healthline, it might be, depending on whether it has:

  • Started growing mold
  • Begun to decay
  • A strong odor
  • Brown skin
  • Bad spots

Those are not good signs, and you should not eat any sweet potato (or other types of potatoes) that displays those characteristics or any other weird growths. Nobody enjoys food poisoning!

However, if the sweet potato feels firm, doesn’t stink, and shows no signs of bacterial, fungal, or mold growth, and if there are no signs of insectile or parasitic infiltration? Then you’re probably safe to cut the sprouts off, properly cook that sweet spud and serve it alongside some butter and sour cream.

(Or, go for something more savory. Sweet potato skins are good with some brown sugar & kosher salt!)


How Do We Store Sweet Potatoes So They Don’t Go Bad?

yummy sweet potatoes after the harvest ready for curing
Harvesting before the weather gets cold is crucial if you want your sweet potatoes to enjoy a long productive shelf-life. When our editor from New England grows sweet potatoes, they’re always a nervous wreck waiting for the first frost. Frost can permanently damage your sweet potatoes – making them turn bad sooner than you had hoped. (We’ve even read from several gardening sources we trust that soil temperatures as low as 50 degrees can damage your sweet potatoes! Frost damage will make your sweet potatoes go bad much faster. They aren’t nearly as cold-hardy as white potatoes.)

Storing sweet potatoes is like storing russet potatoes, white potatoes, or any other type of potato. You keep them in your pantry or another location that stays dark and cool most of the time.

However, there are some things that you can do to ensure that you maximize the time it takes for your sweet potatoes to start to spoil, including the following.

  1. Inspect your sweet potatoes periodically. Look for sprouts, withering, mold, bacteria, fungal growth, softness, or stickiness. If you find potatoes like that, cull them and get them away from your healthy and edible potatoes. Nobody relishes eating sweet spuds with dark spots or soft spots!
  2. You can help keep moisture in your sweet taters by rinsing them in cold water. Then wrap them in damp paper towels and place them inside a perforated plastic storage bag, like a Ziploc. Then, you can put that storage bag in your refrigerator. Sweet potatoes stored in this manner can last several weeks and still be perfectly edible.
  3. You can also extend the storage time of your raw potatoes by cooking and then refrigerating them. Refrigerating should keep them healthy and edible for up to five days. (We’ve eaten them after a week. But the flavor and texture will be inferior by then.)

Finally, you can store your sweet potatoes for up to six months by cutting them into pieces and freezing them. Pack them in freezer bags or any airtight container. Then store them in the freezer for the best shelf life possible.

Helpful Tip: Make sure you put a label on your freezer-safe container with the date on it so that you know when it might be time to discard them. Using a thick magic marker usually works fine. (Or use a label maker with a big font so you can easily read the label!)

Is There Anything We Can Do Once Sweet Potatoes Have Gone Bad?

delicious looking homemade sweet potato fries
Do you have more sweet potatoes than you can eat? Maybe you’re worried about them going bad before you can enjoy them. Then consider making sweet potato fries! Sweet potato fries are a perfect side dish for homemade fried chicken, soups, salads, sandwiches, and stir-fried veggies! And we found a delicious sweet potato fries recipe from the Iowa State Extension. We also found another sweet potato fries recipe on the Mississippi State Extension – this time with spicy sweet potato fries using an air fryer! Don’t forget plenty of ketchup. And sour cream!

Unfortunately, sometimes, even the best sweet potato lies forgotten for too long and falls to decay. It’s heart-crushing to see your harvest go to waste – a rotting sweet potato you neglected to enjoy.

You’ll have to forego the deliciousness of crispy sweet potato chips, salty sweet potato peels, and other lip-smacking sweet potato recipes.

But you have to move on, difficult as it may be.

No food poisoning for us, thanks!

So, what can we do with sweet potatoes that go bad?

Is there a positive way to use them to help the planet instead of just sending them to the dump or landfill?

Yes! There is!

Consider these suggestions.

  • Add them to your compost pile
  • Throw them into the woods and let nature handle it
  • Cut away any good parts and feed them to farm animals

Of course, sometimes, you might run into a sweet potato that has gone South so far that there’s no practical use for it at all anymore. In this case, it’s probably best to discard it in an eco-friendly way.

Final Thoughts About Determining If Sweet Potatoes Are Bad

OK – we did it! We learned how tell if a sweet potato is bad, spoiled, or still safe and viable enough to eat without making us sick. Like most things, it comes down to common sense techniques, like looking for mold growth or noticing that the sweet potato has an unpleasant odor like, well, you know.

Thank you for reading along! And I hope that the information has been valuable. It was a good time for us. Happy Sweet Potatoing! 

(Yes. I made that up!)

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