8 Ways to Know Your Watermelon Is Ripe

Avoid the disappointment of cutting open an unripened watermelon.

Treehugger / Kristine Hojilla

There is nothing quite like the disappointment of biting into what you thought was ripe watermelon, only to experience a bland, unsweetened taste.

Watermelons don't continue to ripen after being harvested, unlike many other fruits. This means that it's no good to just buy one melon and try to let it ripen on the counter. While cantaloupes and other melons tend to get softer after sitting at room temperature for a few days, their sweetness is determined by when they were picked, not by how soft they get on the counter.

Here are eight expert tips on how to tell if a watermelon is ripe for eating, whether you bought it at the market or grew it at home.

Look at the Belly

hand looks at watermelon belly

Treehugger / Kristine Hojilla

Watermelons have an underside, or belly—which is in contact with the ground throughout its growth—called a "field spot." This spot on a ripe watermelon will be yellowish (sometimes referred to as "buttery") and not white, which indicates an unripe melon.

Thump It

person thumps on watermelon with hand

Treehugger / Kristine Hojilla

Using your knuckles, rap on the middle of the watermelon while holding it up to your ear, or flick it with your finger. A ripe watermelon will have a hollow sound when knocked, which sounds more like a "plunk" than a "thwack." An unripe watermelon will have more of a higher-pitched sound, while an overripe one will make a "thud" or a lower-pitched sound.

Learning the difference between the sounds takes a bit of practice. You can also ask a melon grower at your local farmer's market, or the produce manager at the grocery store, to demonstrate it for you so you can hear it for yourself.

Take a Whiff

Pick up the watermelon and carry it a little bit away from the rest of the melons and give it a good sniff. A ripe watermelon should smell slightly sweet, and similar to what a melon tastes like, but not overly sweet—that can indicate an overripe watermelon.

This sniff test also works great on other types of melons, such as cantaloupes and honeydew.

Squeeze the Sides

Gently squeeze the side of the watermelon to see if there's a bit of "give" to it. The rind of the melon shouldn't be soft, as the skin of some fruits gets when ripe, but it also shouldn't be hard as a rock with no give to it at all.

Check Its Weight

If you've gone through the above tests and still can't narrow down your choices between a couple of watermelons, try comparing the weight of similarly-sized ones and pick the one that seems heavier to you. This isn't a fail-proof test, but it can be fairly reliable.

Check the Calendar

hand holds seed packet next to watermelon

Treehugger / Kristine Hojilla

Did you save your watermelon seed package and write down the date you planted them? Many standard commercial varieties of watermelons will be true to their descriptions on the seed package, assuming all other conditions are present: good soil, adequate watering, and lack of pest issues.

A ripe watermelon from these varieties should be approximately the size indicated on the seed package, although that can vary quite a bit depending on the conditions in your garden.

Examine the Vine

watermelon dry tendril held by finger

Treehugger / Kristine Hojilla

The leaves and vine itself should still be green and healthy-looking, but on a ripe watermelon, the tendril closest to the fruit will tend to be brown and dried. If the tendril is still green, the watermelon is probably still ripening. If the whole vine and leaves are getting brown, the watermelons probably won't get any riper, and it might be best to harvest them before they go bad.

Look at the Connection, and Thump Again

hands touch the withered vine of watermelon

Treehugger / Kristine Hojilla

Actually, don't really knock the watermelon off the vine, but rather thump it as described above. A ripe watermelon has a distinctive tone to it, and if all other indicators point to ripeness, the thump test is a good one.

Watermelons don't slip right off the vine, as some other melons do, but the end of the vine near the melon may start to appear cracked or brownish as it ripens. I've not had very good success with this test, but several people have told me they use it as an indicator of ripeness.

Frequently Asked Questions

  • Do watermelons ripen after picking?

    Unlike many fruits, watermelons do not continue to ripen after they've been picked. That's why it's important to know whether a watermelon is ripe before picking or buying it. Once it's been harvested from the vine, it will hardly change until it goes bad.

  • How do you know if a watermelon is sweet?

    When picking a watermelon, you want to see a lot of "webbing," also called "sugar spots." These veinlike markings form during pollination. The more webbing you see, the more pollinated the plant, and the more pollination, the sweeter the fruit will be.

  • When is the best time to buy watermelon?

    In the U.S., watermelon season is between May and September. Make sure you buy domestically grown watermelon to minimize food miles. The top watermelon-growing states are Florida, California, Texas, and Georgia.

  • Which watermelon is sweeter, round or oblong?

    Round watermelons tend to be sweeter and less watery than oblong watermelons.