When grapes are purchased from an outside source, the grower should be contacted early in the season. Grape growers like to have their grapes sold well before harvest time, so purchase arrangements are best made well before the Fourth of July. The grower's harvest criteria should be discussed and carefully considered. Some growers harvest as early as possible each season, and red grapes are often picked very close to 22.5 Brix. Who will pick and the price of the grapes should be clearly established when purchases are made from outside sources.
Harvest time depends on many factors, and picking times vary from year to year.
The grape varieties, vineyard location, soil, weather conditions and irrigation schedules all influence harvest times. Rain late in the season often delays picking by a week or two. Many variables are involved, and accurately predicting when grapes will be ripe is nearly impossible. Consequently, winemakers should keep in touch with the vineyard and follow the development of the grapes as they ripen. Then the winemaker will be ready to process the grapes promptly when harvest time finally arrives.