If you’ve bought a beautiful pint of berries lately, only to open the container and find them covered in a fuzzy coat of mold, you’re not alone. It’s one of life’s small, but very irritating mysteries. You just wanted a snack or to sprinkle them on your morning oats, and instead, you’re left with a science experiment in your fridge that seemingly appeared overnight. What gives, berries?

Why are your berries molding?

Sadly, fuzzy moldy growth and fresh berries can be a common combo. And it’s more than frustrating when you’ve just dropped some serious cash on these tiny delicate fruits. But why does this happen so often?

According to Richard Kim, PhD, plant pathology expert and Director of Pathology at RipeLocker, the culprits here are fungal spores. These microscopic troublemakers are pretty much everywhere—on trees, in the soil, floating through the air, and even in water. Berries naturally come into contact with these spores during their entire lifecycle, from growing to harvest to postharvest handling.

“Unlike other fruits, berries are not washed before being packed into clamshell containers due to their delicate nature, which means fungal spores are not removed,” Kim explains.

Berries are kept as cool as possible during transportation and storage to slow down mold growth—think around 32°F (0°C), per Kim. But here’s where things can take a turn for the worse: “Once the fruit reaches retail stores, temperatures are typically raised to 40°F (4°C) or higher, especially on store shelves,” says Kim. “This temperature shift leads to condensation inside the clamshells, creating a warm, humid environment—ideal conditions for mold growth.”

But the fungal spores aren’t the only consideration to factor, as their size and prized juiciness are also factors. “Berries have high moisture content which promotes microbial and mold growth,” food microbiologist Dr. Susan Harlander shares. “Their thin, fragile skin makes them prone to damage during handling, creating entry points for mold spores which are naturally present in the environment and on the surface of the berries when you buy them.” Harlander adds that improper storage can accelerate this process, too.

Is mold on berries harmful?

You grab a container of strawberries, see a couple with fuzzy spots and think: These few are bad, but the rest look fine. Do I *really* need to toss them all? The answer is, unfortunately, complicated.

“According to the U.S. Department of Agriculture (USDA), if you find mold in berries you should toss that berry and any it is touching as there is a chance of ingesting mold toxins,” per Toby Amidor, MS, RD, CDN nutrition expert and best-selling author of Health Shots. “The other berries in the container are good to eat—as long as they are not soft or discolored.”

When it comes to storage, Dr. Kim warns that “it’s best to avoid keeping healthy berries in the same container [as moldy ones] to prevent further contamination, as invisible fungal spores and mycelia may still remain inside the container.” Try a reusable glass or ceramic vessel that you can wash in-between berry purchases.

How to keep your berries fresher, longer

Fortunately, there are a few tricks to extend your berries’ life (fuzz-free!) and make sure they stick around long enough for your breakfast plans. Amidor has several best practices for buying and storing berries:

• Inspect your berries before buying. Look for visible signs of mold inside the container and check if any berries are sticking to the bottom of the container (they should be free falling). Of course, if you depend on a service—like Instacart—to do your shopping, this may not be possible (but I suppose you can always request that your shopper take this step too).
• Store your berries in a cool, dry place. Keep them in the crisper of the fridge, preferably in their original container with holes or on a paper towel in an open (or ventilated) container.
• Only wash your berries *right* before eating. Washing them earlier may inadvertently add moisture, increasing their chances of molding. If you’re feeling fancy and organized, you can give the berries a quick vinegar bath (1 part vinegar, 3 parts water); this kills off lingering mold spores. Just make sure to rinse them thoroughly with water afterward—no one wants vinegar-flavored fruit. However, “while washing berries with vinegar can help reduce bacteria, it has limited effectiveness against fungal pathogens,” cautioned Kim.
• Clean your refrigerator regularly., Use 1 tablespoon of baking soda mixed in 1 quart of water to help get rid of any pathogens, including mold. This will reduce the amount of germs and spores on and in your fridge that berries will pick up.
• Don’t crowd the berries. Overcrowding may bruise the berries and lead to moisture buildup, which can lead to more chances for mold to grow.

And remember: If fresh berries feel too high-maintenance, you have plenty of equally delicious alternatives. Frozen, dried, and freeze-dried berries are excellent options that provide the same nutrients and flavors as their fresh counterparts, but with a much longer shelf life. (Think: Months, instead of hours or days.) Frozen berries are perfect for tossing into smoothies, dried berries make a convenient and tasty snack, and freeze-dried varieties offer a unique crunch and versatility. With these alternatives, you can enjoy the goodness of berries without feeling the pressure of having to consume them immediately.

It’s always disappointing to open a container of berries, anticipating their sweet, juicy flavor, only to find some unwelcome fuzz. While it may seem like those berries have turned against you, not all hope is lost. Remove the affected ones, check the rest carefully, and when in doubt, it’s best to stay cautious. With proper storage and care, you can keep your berries fresh and ready to enjoy.