Question: When you’re buying whole watermelons, what’s the best way to tell if they’re ripe?
Answer: Watermelon doesn’t ripen any further once it has been picked, so it's worth your while to select it carefully at the store.
You should look for two key ripeness clues when selecting a whole watermelon.
First, lift up a few melons that are about the same size. The melon you want is the heaviest of the bunch — a ripe watermelon consists of more than 90% water, so the heavier the better, says the National Watermelon Promotion Board.
Second, turn the watermelon over and take a look at its underside. It should have a creamy yellow spot from where it sat on the ground and ripened in the sun, notes the Watermelon Board. If you don’t see this spot — or if it’s there, but it’s a greenish-white color instead of yellowish — it’s probably not ripe enough. Take a pass and move on to the next melon.