When you’re shopping for produce in a store, some items make it pretty easy to tell how fresh or ripe they are. Bananas turn from green to yellow to brown, lettuce slowly wilts and bad apples usually have noticeable mushy spots. For other items, it’s sometimes tough to tell what the quality is without knowing what to look for. Here are some tips on measuring ripeness and freshness for a few common produce items.

Artichokes — Fresh artichokes should have tightly closed thistles that squeak just slightly when the leaves are rubbed against each other. By looking at the base of the stem, you can tell how fresh an artichoke is. The longer an artichoke has been cut, the darker brown the base will look.

Avocados — When ripe, an avocado should give just a little bit when squeezed. An avocado that feels like a rock will likely need a few days to fully ripen. At room temperature, a hard avocado usually ripens in three to six days.

Bell Peppers —Bell peppers should have a firm feel with a smooth texture and no wrinkles or soft spots. Soft spots generally indicate that a bell pepper was mishandled during transport.

Cantaloupes — Cantaloupes give off a sweet smell when ripe. An unripe cantaloupe will have a bit of a greenish tint on its outer rind which will become more golden as it ripens. An interesting fact about all melons is that sweetness is determined before the fruit is picked from the vine. Melons will become softer as they ripen, but once removed from the vine, they’ll never become sweeter.

Coconuts — Coconuts are somewhat unique in the fact that the optimal time for use varies based on what the coconut will be used for. Young, greener coconuts will have a sweeter juice in them and will have a gelatinous interior. The longer a coconut matures, the harder the interior becomes, so, an older, browner coconut is better for getting coconut flakes. Shake a coconut to hear if the interior sloshes. If you don’t hear much, the coconut may be going bad.

Radishes—Radishes are best when they have a smooth, colorful texture and fresh-looking leaves. Radishes develop white spots after rubbing against one another in bunches for extended periods of time, indicating that their freshness is fading.

Pineapples — A ready-to-eat pineapple will usually look yellowish between the scales with just a little bit of green. Pineapples give off a sweet aroma when ripe. They don’t give off much of an odor at all if they’re not ripe yet, and they will begin to smell fermented if they are overripe. There is a common myth that you can tell that a pineapple is ripe if you can easily remove a leaf from its crown, but that actually reveals nothing about the interior of the fruit.

Potatoes — Potatoes are a hearty produce item with a long shelf life. They can be eaten at any stage until they spoil. New potatoes are actually immature potatoes harvested before they fully develop; they’re not a unique potato variety. Although sprouts may appear scary, they don’t necessarily mean that a potato is bad. It is usually fairly easy to tell when a potato has begun to spoil, as they darken, wither and give off an unpleasant odor as they rot.

Watermelons — A well-ripened watermelon should have a yellowish bottom. If the stripes are a consistent green color all the way around, the watermelon is probably not ripe. Thumping a watermelon’s outside can also give you some indication about its contents. The riper they are, the more hollow watermelons sound.