The following article is courtesy of the Scott County Cooperative Extension Service:
Pick a ripe watermelon every time in two easy steps
: Look for melons that are heavy for their size and have a firm rind. Remember, watermelon is mostly made of water. So if it feels light, that means your main ingredient is lacking.
: Turn the melon over and look at it’s underside, which sits on the ground. This field spot should be yellow or cream colored, indicating the watermelon was allowed to ripen in the field before harvesting. If it is white or pale green the melon was harvested too early. If grown hydroponically, there will not be a field spot on it’s underside and the watermelon should be labeled as such. Watermelons do not continue to ripen after they have been removed from the vine. So, they should be harvested when they are ready to eat. No amount of thumping, taping, sniffing, or shaking accurately indicates ripeness. Depend on what you see to help you choose the best watermelon.
Special thanks for Lindsey Sexton for writing this blog post on the Arkansas Food Blog. For more info on properly preparing and storing watermelon, visit: https://www.uaex.edu/life-skills-wellness/food-nutrition/eating-well/arkansas-foods-blog/posts/select-a-watermelon.aspx