Photo used for illustrative purposes.

Summer is filled with mysteries. Case in point: Why can some people consistently pick the most flavorful, crisp watermelon for every picnic or potluck, while I invariably choose clunkers — mealy and mushy — that seem to contain notes of sawdust?

This is why I asked melon grower Jeff Nistler to show me around his Maple Plain farm where he tends to five varieties of watermelon and nine kinds of cantaloupe. If anyone could detect a delicious melon, it's Nistler.

Here are some tips for purchasing this picnic table staple — just in time for the last few summer gatherings.

Look for the field spot

This is Nistler's top piece of advice, by far. When a watermelon rests on the ground, it develops a field spot. For typical melons that have the green rinds with jagged stripes, the field spot should be yellow, rather than white or a pale green, for optimum ripeness. For melons that are more solid and dark on the outside — like the Black Diamond variety — the field spot should be a deep yellow, turning orange.

 Jeff Nistler cut up a watermelon at his Nistler Farms in Maple Plain. 

"You wish you could have a spectrometer to see into (the melon), but you can't. So it really comes down to that yellow spot," he said.

Feel it in your hands

My Star Tribune colleague food writer Joy Summers tells me that a good melon should feel heavy for its size. Pick up the melon and compare its weight to others roughly the same size. I use this trick with other produce, especially oranges, but it holds true for melons, too. The denser it is, the more water it likely holds. And who doesn't love a juicy melon?

Tap it

A young vendor at a roadside farm stand once told me the tastiest watermelons should sound hollow. "It's counterintuitive, right?" he said. He even knocked on several for me, as if playing the marimba, before picking the most hollow-sounding. (And yes, it was delicious.)

 Jeff Nistler showed the stem of the melon. 

Nistler cautioned that the sound isn't as important to him as other indicators, but that often a good melon will typically sound "tight like a drum."

Smell it

For cantaloupe and musk melon, don't be afraid to put your nose right up to the stem end. (This trick doesn't work for watermelon.)

"You should be able to smell a sweetness to it," Nistler said. "If it doesn't have the aroma, it's not ripe — or it's not good."

That doesn't mean it doesn't have the potential to become ripe. If the scent isn't there, let the melon sit on your counter for a day or two. "You'll know for sure when it's ready," he assured me.

Nistler says that on a recent weekend, most of his customers were smelling the wrong end of the melon. The part that was attached to the plant's flower may smell like dirt, but the stem side will carry that sweet scent if it's ripe.

Tribune News Service