Fresh Herbs

Fresh herbs divide into two groups that need opposite treatment, and this is the single most useful thing to know about them.

Tender herbs — parsley, cilantro, mint, dill, basil — should be treated like cut flowers. Trim the stems, stand them in a jar with an inch of water, cover loosely with a bag, and refrigerate. They keep 1–2 weeks this way instead of 3 days in a bag.

Basil is the exception to the exception: keep it on the counter in water, never in the refrigerator. It suffers chilling injury and blackens.

Hardy herbs — rosemary, thyme, sage, oregano — should be wrapped in a slightly damp paper towel and kept in a bag in the crisper, where they last 2–3 weeks.

Herbs freeze well chopped in oil or butter in ice cube trays. Hardy herbs also dry well; tender ones mostly do not.

The split between tender and hardy herbs is a split between two kinds of plant tissue.

Tender herbs have soft, thin, high-moisture leaves with minimal cuticle — closer to a salad green than to a shrub. They wilt through simple water loss, which is why standing them in water works: the cut stems draw water up and restore turgor exactly as cut flowers do. They also respire quickly and break down fast once cell walls are compromised.

Hardy herbs are woody perennials from Mediterranean climates, with thick waxy leaves adapted to resist drought. They lose water slowly and contain high concentrations of aromatic oils that are mildly antimicrobial, which is why they last weeks rather than days and why they dry well without losing their character.

Basil is the odd one out because it is a tropical plant, and it suffers chilling injury below about 50°F. Refrigeration damages its cell membranes, and the leaves blacken within a day or two. It belongs on the counter in water, out of direct sun.

Herbs are also a genuine source of foodborne illness — cilantro, basil, and parsley have all been linked to outbreaks, since they are grown close to the ground and eaten raw. Wash them well.

Discard herbs that are slimy, blackened, or smell fermented.