How to Tell if a Watermelon Is Ripe

Avoid the disappointment of cutting open a watermelon, only to find that it's not fully ripe and sweet, with these simple tips.

Watermelons are one of my favorite summer foods, followed closely by cantaloupes and other melons, and to my mind, nothing tastes like summer like a sweet and crunchy watermelon. On the other hand, there's nothing quite like the disappointment of biting into what you thought was a ripe watermelon, only to be rewarded by the bland and flavorless taste of an unripe melon. I don't know if there's a word for that feeling, but there really ought to be.

Watermelons don't continue to ripen after being harvested, unlike many other fruits, so it's no good to just buy one and try to let it ripen on the counter. Cantaloupes and other melons do tend to get softer after sitting at room temperature for a few days, but from what I understand, their sweetness is determined by when they were picked, not by how soft they get on the counter.

To help do my part for world peace by reducing the disappointment of eating an unripe melon, here are a few 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 its belly: 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: Using your knuckles, rap on the middle of the watermelon while holding it up to your ear, or flick it with your finger (like flicking a crumb off your shirt). 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 of an unripe vs. a ripe watermelon takes a bit of practice, but one way to get a head start on it is to ask a melon grower at your local farmers market (or perhaps the produce manager at the grocery store) to demonstrate it for you so you can hear it for yourself.

Sniff it: Pick up the watermelon and carry it a little bit away from the rest of the melons (so you don't pick up the smell of other 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 (which can indicate an overripe watermelon). This sniff test also works great (actually, even better than for watermelons) on other types of melons, such as cantaloupes and honeydew.

Squeeze it: 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 get when ripe, but it also shouldn't be hard as a rock, with no give to it at all.

Heft it: 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 I've found it to be fairly reliable (although since I don't tend to buy two similar melons and compare them after cutting them open, this may be more of an indication that I've already picked the ripest ones with the thump test).

Watch the calendar and break out the measuring tape: You did remember to save your watermelon seed package and write down the date you planted them, didn't you? Many of the standard commercial varieties of watermelons grown in home gardens will be true to their descriptions on the seed package, assuming all other things are equal (good soil, adequate watering, lack of pest issues), so it's good practice to keep track of when those melons 'should' be ripe before trying to harvest one. And 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.

Check the field spot: As mentioned above, gently turn the watermelon over and look at its belly to see if it's more on the yellow spectrum (ripe) or if it's still white (unripe). This is also a good opportunity to check for and remove slugs or sowbugs or other critters who may be looking to dine on the melon at your expense.

Examine the vine: 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.

Knock it off: 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.

Look at the connection: 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.

Happy (ripe) watermelon hunting!