When should grapes be harvested?
Grapes should not be harvested until fully ripe. The best indicators of ripeness are color, size, and flavor.
Depending on the variety, the berry color changes from green to blue, red, or white as the grapes approach maturity. At the fully ripe stage, the natural bloom on the berries becomes more pronounced. However, color alone should not be the sole basis for harvesting grapes. Many varieties change color long before the grapes are fully ripe.
Size and firmness are other useful indicators of ripeness. The individual berries should be full-sized. They also become slightly less firm to the touch at maturity.
The final and most reliable test for ripeness is flavor. Taste a few grapes when size and color are good. If they are not sweet, leave the clusters on the vines. Grapes do not develop full flavor when harvested before completely mature.