A Big Complaint Customers Have With Costco Mushrooms

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Costco's produce section is great for buying in bulk at a good price, but there's a catch: Since you're buying fruits and vegetables in large quantities, your household will need to be able to consume all of them before they spoil. This is proving to be an issue with the large boxes of mushrooms sold at the warehouse retailer — at least, that's what many Costco members are saying. Customers have reported that they have an incredibly short shelf life, and they've even spotted rotten and moldy mushrooms in the store.

In a Costco group on Facebook, a frustrated shopper wrote, "Grrrr bought mushrooms, three days later all rotten." Another customer shared a similar experience on Reddit, posting a photo of deteriorating mushrooms alongside the question: "Is it me, or are other people's veggies going bad QUICK?" One customer made a Facebook video that showed multiple packages of mushrooms sitting on store shelves with squishy brown spots and visible mold. 

These complaints were not specific to one type of mushroom; customers reported experiencing this with both white and crimini mushroom varieties. Comments on these social media posts also point out general disappointment with Costco's produce section, but the high moisture content of mushrooms makes them spoil more quickly than other produce.

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Fortunately, there are several ways to extend the shelf life of mushrooms at home. First, make sure you're picking a good box of mushrooms at Costco, or any other store. To tell if the mushrooms have gone bad, look for obvious signs of mold or sliminess. White mushrooms sometimes turn brown and squishy, and older mushrooms start to shrivel. If you see a lot of condensation on the outside of the box, opt for another one if possible — this water buildup leads to mold. 

Plastic wrapping over a box is one of the worst ways to store mushrooms, as it traps moisture in. At home, take them out of the container, and pat any damp-looking mushrooms with a paper towel. Avoid washing immediately, because this introduces extra water. Transfer the mushrooms to a paper bag so they can breathe and release moisture, and keep them stored in the fridge. Wrapping them in paper towels and placing them in a bowl or bag also works.

If you notice one moldy or slimy mushroom, remove it and inspect others to ensure the spoilage is not spreading. Sliced mushrooms may last a few days in the fridge, but whole ones can keep up to a week if stored correctly. These storage tips are for the standard white and brown mushrooms sold in most grocery stores. Specialty mushrooms like morels are stored differently, either in the freezer or with a bit of moisture.