Watermelon +Watermelon can be sliced and eaten alone, used to make glazes and sauces, grilled and stir-fried and baked. Before cutting into a watermelon, wash the watermelon and your hands. Cut watermelon can be refrigerated for up to seven days, but should be kept in an airtight container. Uncut watermelon can last up to three weeks. Watermelon can be quick frozen by cubing it and placing it on a tray in the freezer.