Watermelons are sold whole, or cut into halves, quarters, or smaller pieces. Skin color ranges from deep green to gray, solid to streaked or dappled.
Look for a melon with a rind that is neither very shiny nor very dull, but shows a waxy “bloom.” The underside should have a creamy-white spot (where it sat on the ground as it ripened in the sun). This so-called “ground spot” changes from pale white to a creamy yellow at proper harvest maturity. If the stem is still attached, it should look dry and brown. If the stem is green, the melon was picked too soon. And if the stem has fallen off, the watermelon may be overripe.
If your market sells cut melons, the fruit should be perfect for immediate consumption—it will not improve once it is cut. With cut melons, you can check the color and texture of the flesh, and usually smell the delectable fragrance of a ripe melon even through the plastic wrapping.
Cut watermelon should have dense, firm flesh that is well colored for its type, with dark seeds. If the piece of melon has seeds that have begun to separate from the flesh, white streaks, or large cracks in the flesh, don’t buy it.