How to Tell If Mint, Dill, or Arugula Has Spoiled

Tender fresh herbs such as mint, dill, and arugula spoil more quickly than many other vegetables because they have a high water content and broad leaf surfaces. The earliest sign may be the bright green color fading and turning yellow, first around the leaf edges and then across the whole leaf.

What should you look for?
After yellowing begins, black or dark brown spots may appear on the leaves. They can start as small marks and quickly spread across much of a leaf. Arugula is especially prone to dark spots, and spotted leaves may also taste bitter. Slick stems or stems that feel watery and limp when pressed between your fingers can also indicate a loss of freshness.

What do smell and texture tell you?
Fresh mint has a sharp, fresh smell; dill has a mildly lemony smell; and arugula has a distinct, mildly bitter, peppery aroma. If these smells fade and are replaced by a damp, rotten odor, that is a strong sign of spoilage. White, fuzzy mold between leaves is another definite sign. In a bunch stored in a damp place, mold may spread throughout the bunch within a few days. Eating a wet bunch with a rotten smell may cause stomach upset and, in some cases, food poisoning. Discard a questionable bunch instead of trying to wash and sort through it.

How long do these herbs stay fresh in the refrigerator?
Mint, dill, and arugula wrapped in a damp paper towel and stored in a loosely closed bag may stay fresh in the refrigerator for 5–7 days. If left dry in a bag, they may begin to yellow and wilt within 2–3 days. Mint and dill with trimmed stems placed in a glass of water and loosely covered with a bag in the refrigerator may last somewhat longer than herbs stored with the paper-towel method.

If part of a bunch has started to yellow, remove that portion promptly. Yellowing leaves release ethylene gas that speeds spoilage in nearby healthy leaves. The three herbs also differ in how quickly they wilt: dill, with its thin, delicate stems, tends to wilt fastest; arugula's broad leaves may make it somewhat more resistant to moisture; and mint, especially varieties with thicker stems, may stay fresh longer. Knowing these differences can help you decide which herb to use first after shopping.

When you wash the herbs can also affect freshness. If they are washed before storage and not dried thoroughly, moisture between the leaves can speed decay. Wash them on the day they will be used, rather than before refrigeration, and use a paper towel to manage moisture during storage. At the store, check the base of the bunch near the stems. A bunch that looks fresh on top but has wet, darkened stems underneath may have been on the shelf for a while and may need careful sorting at home. Store mint, dill, and arugula separately so you can monitor how quickly each one spoils.