It should be a sure thing: Summer gardens produce green beans and tomatoes and zucchini.

So it's easy for a novice gardener to assume that he or she did something wrong when a garden doesn't produce a bountiful harvest.

But it turns out that our vegetables are more sensitive to hot weather than many of us realize. For the past couple of summers, we've had unusual heat waves that have disrupted the ability of flowering vegetables to bear fruit.

Perhaps the poster child this year has been the vining green bean. Gardeners report lush vines covered in white blossoms that should be developing into beans. But that simply hasn't happened. Here it is August, and not a bean on some of these plants.

Kathleen Cue, horticulturist with the University of Nebraska-Lincoln Extension, explains why high temperatures have been a problem this summer:

Pollination is the process by which certain plants develop an edible vegetable.