Learn what goes on in the vineyard and winery during each stage of the annual harvest for wine grapes.Sports teams have playoffs. Students have finals. And for winegrowers, the big sink-or-swim moment—the event the whole year's efforts have led up to—is harvest. The period culminating in grape crush begins when the grapes start to change color in mid to late summer. The actual picking of the grapes usually happens between August and November above the equator and February to April below. What happens in between is the greatest determinant of a wine's quality in a given vintage. Read on to learn about the processes—and perils—of harvest season.