Veraison signals the coming of harvest. It is the stage of the ripening process when grapes begin to soften and change their color. At the beginning of veraison, the berries are hard, green and about half the size they will reach when fully mature. In addition to the outward changes to the berries, this 30 to 45 day period marks an increase in the level of brix, or fermentable sugar produced in the grapes.