How to Choose and Ripen Plums

A ripe plum yields slightly under gentle pressure near the stem; if the flesh around the pit is still rock-hard, the plum is not ripe yet. A dull, whitish coating on the skin, called bloom, is also a natural sign of freshness, not dirt to wipe off. Firm plums can be ripened at room temperature in a paper bag for a few days. Refrigerating plums before they ripen largely stops the softening process, so getting the order right directly affects their flavor. Even the most commonly sold varieties can stay hard and tasteless if these two steps are skipped.

How Can You Tell When a Plum Is Ripe?
The most reliable test is a gentle-pressure test: hold the plum in your palm and press lightly with your thumb near the stem. A ripe plum yields slightly to the pressure, while a firm plum remains unchanged. The second sign is smell; ripe plums give off a lightly sweet, tart aroma when brought close to your nose, while plums with no smell are usually still underripe. The skin should also have a fully developed color; areas that remain greenish indicate that ripening is not complete.

How Do You Ripen Firm Plums?
Place firm plums in a paper bag and close it loosely; ethylene gas released by the plum itself builds up in the bag and speeds ripening. Adding a ripe apple or banana to the bag shortens the process further. Keep the bag at room temperature in a place out of direct sunlight; plums generally soften noticeably within 2–3 days. Choose paper instead of a plastic bag, because plastic traps moisture and makes mold more likely.

When Should Plums Go in the Refrigerator?
Refrigerate plums only after they reach the desired ripeness. Cold air greatly slows the plum’s softening process; putting a firm plum in the refrigerator nearly stops its ripening. Ripe plums stay fresh in an uncovered container in the refrigerator for 3–5 days. Let them sit at room temperature for a few minutes before eating to make their aroma more noticeable.

What Signs Should You Avoid When Buying Plums?
Plums with wrinkled, sponge-like skin have usually been stored too long and lost moisture; the inside may also be dry. If there are bruises or sunken, soft spots, decay may have started there, so avoid buying them. Do not choose plums with moisture or signs of mold where the stem has come off. If you smell a sharp, mold-like odor rather than a mildly tart one, the plum is no longer fresh.

What Can You Do with Overripe Plums?
Do not waste plums that have become soft enough to mash; remove the pits and turn them directly into jam or compote, or store them in the freezer. Cutting them into two pieces and removing the pits before freezing makes them easier to use later. If eating very soft plums raw, briefly rinse them in cold water and eat them right away; they should not be left sitting for long, or the skin may split and the juice inside will start to run. Frozen plum slices can be added directly to cake batter or compote without thawing; this saves time and prevents the plums from releasing extra water and making the batter runny. The slices keep most of their flavor for several months in the freezer, but should be stored in a tightly sealed container.