What Season Are Grapes Ripe?

General Time Frame

• Most grape varieties ripen between mid-August and late September. As grapes approach maturity, their color changes from green to red, purple or white. The grapes grow in size and become slightly less firm. However, the best indicator of maturity is taste. Grapes have a sweet, rich flavor when ripe.

Variety

• Grapes vary in ripening times depending on the variety. Tender varieties used for wine or table use tend to ripen earlier than hardy grape varieties reserved for jellies and juice. Aurore, Himrod and Millot are table or wine grapes that ripen from late July to early August; Hardy Concord grapes are very late, ripening in late September.

Growing Conditions

• Grapes ripen faster when planted on a slight slope with a southern exposure. Good air circulation and full sun prevent disease problems and also hasten ripening. Grapes planted in low areas or on northern slopes ripen more slowly because these areas are cooler throughout the growing season.

Considerations

• Grapes do not ripen further after picking, so taste them to ensure they are completely ripe. Grapes generally ripen at the same time every year unless the weather is unseasonably cool or rainy. Keep notes describing ripening times so you know when to expect grapes to mature. Cut the grapes with a sharp knife and sort them, removing any that are soft or show signs of decay. Store the grapes in perforated bags in the refrigerator.