How long do fresh mushrooms last in the fridge?

The honest range: whole mushrooms, stored somewhere they can breathe, usually last five to seven days in the fridge. Sliced or pre-cut mushrooms last a lot less — closer to three or four days — because cutting takes away the one thing holding the spoilage back. Cooked mushrooms keep for roughly three to five days in a sealed container. None of this is really about a mushroom going "off" the way a carrot does. A mushroom is a fungus, not a vegetable, and almost everything about how it behaves in the fridge follows from that one fact.

Why a mushroom is not a vegetable and does not act like one

Most vegetables are protected by a skin that holds moisture in and keeps the outside world out — a pepper's glossy shell, a carrot's tougher outer layer. A mushroom has nothing like that. Its cap is closer to a sponge than a skin, and the gills underneath sit exposed to the air, constantly giving up moisture or soaking it back in depending on what is around them. Mushrooms are also roughly ninety percent water by weight, which is unusually high even by produce standards, and they have no ripening pause the way a tomato or an avocado does — there is no window where a mushroom is quietly getting better on the counter. From the moment it is picked, the only question is how the water inside it is managed, not how much sugar or ripeness it still has to develop.

Why the sealed tray works against you

Mushrooms are usually sold on a foam tray wrapped tightly in plastic film, and that packaging is built for the shop shelf, not your fridge. A sealed wrap traps every bit of moisture the mushrooms give off, and with nowhere for it to go, that moisture condenses right back onto the caps. A mushroom sitting in its own condensation for four or five days is exactly how you end up with the slimy, faintly wet surface that makes people throw out a punnet that still had a day or two of real life left in it. The better home for mushrooms is something that lets moisture escape: a paper bag, the original tray with the plastic swapped for a loose sheet of paper towel, or an open bowl covered lightly rather than sealed. None of this requires buying anything — it is simply not resealing them the way the shop did.

Why a sliced mushroom spoils so much faster than a whole one

A whole mushroom's cap, thin as it is, is still the only barrier it has, and once you slice through it that barrier is gone entirely on the cut face. There is no skin left to slow moisture loss or keep bacteria on the surface rather than in the flesh, so a cut mushroom is essentially unprotected from the moment the knife goes through it. This is why a punnet sliced at the shop, or sliced by you and left for "later in the week," turns so much faster than the same mushrooms would have if they had stayed whole. The practical version of this is simple: buy whole where you can, and slice only the amount you are actually cooking that session, rather than prepping the whole punnet in advance to save five minutes later.

Normal aging versus actually spoiled

Mushrooms darken and shrink a little as they age, and the surface can turn slightly wrinkled or leathery as they lose moisture — that is completely normal and does not mean the mushroom is unsafe, especially if you are cooking it rather than eating it raw in a salad. What actually signals the end is different: a slimy, tacky film across the surface, a pool of dark liquid collecting underneath the mushroom, or a strong sour or ammonia-like smell rather than the usual mild, earthy one. It is also worth knowing that many mushrooms naturally carry a fine white, cottony bloom on the cap or stem that is not mould — genuine mould shows as fuzzy patches, often blue-green or black, that were not there before and are growing rather than static. When in doubt, the smell is the most reliable test here: a mushroom past its best still smells like a mushroom, just less so, while a spoiled one smells distinctly wrong.

What actually helps

• Swap the sealed plastic for something breathable. A paper bag or a loosely covered bowl lets moisture escape instead of condensing back onto the caps.
• Do not wash mushrooms before storing them. A mushroom is already mostly water and readily absorbs more; wipe with a damp cloth or give it a quick rinse right before you cook, not days in advance.
• Buy whole and slice only what tonight's dinner needs. The cut surface is where spoilage actually starts, so the fewer cut surfaces sitting in the fridge, the longer everything lasts.
• Judge by smell and touch, not just colour. Darkening alone is normal aging; sliminess and an off smell are the two signs that actually mean it is time to throw it out.

Mushrooms are also a classic case of the half-used punnet that quietly disappears behind something taller on the shelf, because there is no printed date to glance at and remind you it is there — just a small brown container that stops registering after the first day or two. Munch logs each batch with the day it went in and where it is stored, fridge, freezer or pantry, shared with everyone in the house, so the rest of a punnet with a couple of days left surfaces in the same list as everything else, instead of losing quietly to whatever gets put in front of it.