Harvest: Scholarly dissertations and humorous pieces alike have been written on how to tell when a watermelon is ripe. It’s important information; watermelons will not continue to ripen after they are picked. The best way is to thump the melon and listen for the “thunk.” For added insurance, the tendrils near the stem should have begun to wither and turn dark, and the underside of the fruit should be changing to a yellowish color. Cut, don’t pull, the stem from the vine.More: Guides to growing the top summer crops