How long do leeks last in the fridge?

The short version: a whole, untrimmed leek wrapped loosely and kept in the crisper drawer is usually good for one to two weeks, sometimes a little longer. Slice it, and that window collapses to about three to five days. The gap between those two numbers is not about leeks turning bad quickly. It is that most of what keeps a leek fresh is a set of outer layers, and slicing is the moment you cut through the thing that was doing the protecting.

Why the outer layers are doing more work than you think

A leek is built like a set of nested tubes, each one wrapped around the next, from a tough outer layer down to a pale, tender core. That structure means the outermost layer or two takes almost all of the damage — the drying, the scuffing, the light browning — while the layers inside it stay essentially untouched. It is the same idea as a cabbage's outer leaves or an onion's papery skin, except a leek's sacrificial layer is still fleshy, so it looks like part of the vegetable rather than an obvious husk to peel off and discard. That is exactly why people sometimes throw a whole leek out when the outside looks tired: what they are looking at is the layer that was supposed to look tired, doing its job.

Where the trapped grit actually comes from

Leeks are traditionally grown hilled — soil is mounded up around the stem as it grows, specifically to block sunlight and produce the long, pale base people want. That means grit works its way down between the layers before the leek is ever pulled out of the ground, not after a week in your fridge. Finding a little sand near the root end is evidence of how the vegetable was farmed, not a sign anything has gone wrong in storage. It is also the reason the usual advice is to slice a leek first and then fan the rings apart under running water, rather than rinsing a whole trimmed leek and hoping water finds its way between layers that are still closed tight.

What actually keeps a whole leek going

Two things matter more than anything else, and both follow directly from how the vegetable is built.

Leave it untrimmed for as long as you can. The roots and the dark green top are usually the parts you cut away before cooking, but until then they are functioning as extra protective layers. Trimming a leek the moment you get home from the shop, rather than right before you cook it, is giving away days of shelf life for no benefit.

Give it a little humidity without sealing it in. A loosely closed produce bag with a couple of holes, or a paper towel wrapped around it before bagging, strikes the balance — enough moisture retained to stop the outer layer drying out fast, without trapping so much that condensation sits against a damaged spot and starts real rot. Standing a leek upright in a jar with an inch of water at the base, the same trick that works for celery and fresh herbs, extends things further still, because the cut root end can draw water back up through the same channels that were losing it.

Once it is cut, the clock resets

Slicing a leek exposes inner rings that have never touched air, and they dry out at the cut face far faster than the intact vegetable ever did. A sealed container, ideally with a barely damp paper towel against the cut pieces, is the best you can do, and it is realistically good for three to five days rather than weeks. Freezing sliced leek is a genuinely good option here in a way it is not for something like lettuce, because leeks are almost never eaten raw for their texture — they go into soup, stock and stir-fries, where the slight softening freezing causes costs you nothing. Frozen sliced leek can go straight from the freezer into a hot pan or a simmering pot.

What is actually spoiled, versus just cosmetic

• An outer layer that has gone dry, yellow or papery. Peel it off and use what is underneath. This is the leek's own protection doing exactly what it is supposed to do, not a sign the rest is going.
• A slimy layer once you peel the outer one back. That is bacterial, not dehydration, and that ring is finished — cut it away and check the layer beneath before deciding about the rest.
• A dark, soft spot that spreads rather than staying put. Cosmetic browning at a cut edge stays small and dry. A spot that is soft, wet-looking and getting bigger over a day or two is real decay.
• A sour or genuinely off smell. A fresh leek smells mild and faintly grassy, closer to a spring onion than anything sharp. An unpleasant smell is the most reliable signal here, more reliable than how the outside looks.

A leek is also an easy thing to half-forget, because most recipes call for one or two and leave the rest of the bunch behind, still wrapped in the bag it came home in. Munch logs a batch like that against the day it arrived and the shelf it is sitting on, so the second half of a bunch bought for one soup shows up again when it is worth using, rather than surfacing three weeks later as a question mark at the back of the crisper.

None of this needs a separate rule for every day a leek sits in the fridge. It needs one distinction: the outer layer and the inner core are not ageing at the same rate or for the same reason, and leaving that outer layer in place — root, green top and all — for as long as possible is most of what "storing a leek well" actually means.