Here are a few pointers on how to pick a ripe and fresh watermelon. Nothing is worse than coming home to an unripe watermelon. Pick up the watermelon and buy a watermelon that is heavy for its size. I like to pick up a handful to really gauge which feels heaviest. Next you will look for the field spot. This is a yellow-brown spot where the vine was. This means it was ripened on the field. Without this spot it means your watermelon could be under-ripe.