Once you've figured out how to pick a watermelon at the supermarket and even mastered the art of slicing a watermelon into bite-size pieces, it's time to learn how to store a watermelon so you can keep that melon fresh for as long a possible. The good news is that the shelf life of watermelons is pretty long: about three to four weeks from when it's picked off the vine, according to the experts at the National Watermelon Promotion Board. The easiest way to store a whole watermelon is probably on your kitchen counter, at or just below room temperature. That's also probably the best way to do it to preserve both texture and quality. But you need to remember that window includes the amount of time spent shipping the fruit to the grocery store—so once the watermelon is on your counter, you only have about a week to use it.
If you're worried about your watermelon spoiling, you can pop the whole thing in the fridge; FreshDirect says that you can keep a whole watermelon in the fridge for up to three weeks, at best. But there's also some research that indicates a watermelon stored in the fridge has a slightly lower nutritional content than one that's been consistently stored at room temperature. So you don't necessarily worry about making space in your fridge for a whole watermelon, especially if you're going to use it in a day or two.
You should, however, definitely refrigerate a watermelon once you slice into it. That's because the fruit's shelf-life shortens dramatically once you cut it. According to the NWPB, you've only got three to five days to make the most of those watermelons slices. The best way to store watermelon after it's been cut is in the fridge. If you've got slices or cubes, put them in a sealable container. If it's a portion of the whole watermelon, still in the rind, cover the pink part with plastic wrap.
If you still have a lot of watermelon left over that you're not going to eat before the end of the week, you can freeze pieces for up to a year. Simply put the watermelon into a sealable container or plastic bag, or place them on a wax paper-lined tray, and pop them into the freezer. Just know that once you freeze watermelon, you basically have to eat it frozen. That's because "Watermelon will lose its taste, texture and color in the defrosting process," according to the NWPB. But frozen watermelon chunks can be used in lieu of ice cubes in cold drinks, like lemonade or even seltzer, or added to smoothies.