Garlic

A whole head of garlic keeps 3–5 months in a cool, dark, well-ventilated place — not the refrigerator, not a sealed container.

A mesh bag, a slotted ceramic garlic keeper, or an open basket in a cupboard all work. Airflow is essential; sealed containers trap the moisture garlic gives off and lead to mold and premature sprouting.

Once you break the head, individual cloves keep about 10 days.

Refrigeration makes garlic sprout faster, not slower — cold is the signal a bulb interprets as winter ending. Peeled cloves are the exception and do belong in the fridge, for about a week.

Garlic freezes well, whole or chopped, for several months. Chopped garlic frozen in oil in an ice cube tray is convenient — but see below, because garlic in oil at room temperature is genuinely dangerous.

Garlic is a bulb, built to survive dormancy underground, and its high sulfur compounds are antimicrobial. That is why a head lasts for months where most produce lasts days.

Its one serious hazard is specific and worth stating plainly. Garlic stored in oil at room temperature can cause botulism. Garlic grows in soil and can carry Clostridium botulinum spores. Oil creates an oxygen-free environment, garlic is low in acid, and at room temperature those spores can germinate and produce botulinum toxin — one of the most potent toxins known, and one that is odorless, tasteless, and not destroyed by ordinary cooking.

There have been documented outbreaks from exactly this. Homemade garlic-in-oil must be refrigerated and used within a few days, or frozen. Commercial garlic-in-oil products are acidified with phosphoric or citric acid specifically to prevent this, which is why they are safe on a shelf.

Ordinary garlic problems are mundane. Green sprouts in the center of a clove are safe, if slightly bitter — remove them. Cloves that have gone soft, brown, shriveled, or developed dark powdery mold should be discarded.

A blue-green tint in pickled or cooked garlic is a harmless reaction between sulfur compounds and trace copper.