I’m not sure there is a food in the world that says “summer” more than watermelon.

Although it’s early in the season, we eat it at Memorial Day cook-outs. The Fourth of July isn’t a proper celebration without this tasty treat. And we say good-bye to meteorological summer with a cold, crisp melon on Labor Day weekend. And don’t forget all those family reunions and backyard barbecues in between.

For lots of reasons, I didn’t get to know my dad’s parents very well, but I do remember visiting them on their farm north of Valentine and gazing in wonderment at the fields of bright...