The most familiar method to check a watermelon's ripeness is to thump the rind with a finger. If this produces a muffled, hollow sound, it is ripe. The sound of an immature fruit, when thumped, resembles a clear, metallic ringing sound. Another way to describe the tones elicited by thumping is a "ping" for unripe or a "pong" when ready. If a markedly dull thud results, the melon has probably reached a state of overripeness.
Besides thumping, you can gauge a watermelon's ripeness by turning it over and observing the lighter-colored patch where it lay on the ground. When this changes from pale green or cream to gold or orange, the melon is likely to be ripe. As a watermelon approaches maturity, the vine's tendrils begin to turn brown and die off. Ripe watermelons often develop a sweet aroma at the stem end, though not as pronounced as that of a ripe cantaloupe. The Smart Gardener website points out that one unique heirloom watermelon, the "Royal Golden" hybrid, makes determination of ripeness easy -- its rind becomes a brilliant golden-yellow when it is mature. 041b061a72