Celery

Celery keeps 3–4 weeks refrigerated when stored properly, and about a week when it is not — one of the widest gaps of any vegetable.

The method that works: wrap the whole head tightly in aluminum foil and put it in the crisper. This sounds like folklore but has a real basis — the foil allows the ethylene celery produces to escape while still limiting moisture loss, whereas a sealed plastic bag traps ethylene against the stalks and accelerates their decline.

The alternative is to stand cut stalks upright in a container with an inch of water, covered loosely, changing the water every few days.

Keep celery away from strong ethylene producers such as apples and bananas.

Celery does not freeze for raw use — it turns limp and stringy — but freezes fine chopped for soups and stocks, where texture does not matter.

Celery is around 95% water held under pressure in long fibrous cells, and its crispness is entirely a matter of turgor — water pushing outward against the cell walls.

That makes limpness a hydration problem rather than a spoilage one, and it is reversible. Cut an inch off the base and stand the stalks in ice water for a couple of hours and they will draw water back up through the vascular bundles and firm up again. This works remarkably well and is worth doing before assuming a head is finished.

Celery is also a significant ethylene producer as well as being sensitive to it, which is the reason the foil trick outperforms a plastic bag: plastic traps the gas, foil lets it vent.

What is not reversible is soft rot. Bacteria that produce pectin-degrading enzymes break down the cement between cells, giving the characteristic slime. Slimy celery should be discarded, not revived.

Hollow or pithy stalks in the center are a growing condition, present from harvest, not a sign of age. Brown streaking on the ribs and a rubbery, wet texture are age.