Blackberries usually go from green to red in 1 to 3 days and red to black in 1 to 2 days. They can be picked when they turn black, but for optimum flavor, they need 1 to 3 additional days for fruits to complete swell and flavor development. Rots are a problem, so harvests should be prompt and frequent. Color break and taste should generally be used in determining when to harvest grapes. Bunch and muscadine grapes have major rot problems and should be harvested promptly once they are fully ripened.
Red color is used to determine harvest date for strawberries.
For maximum flavor, berries should be harvested when fully red. If fruit are being shipped, they must be harvested when slightly on the firm side when some fruit may not be completely red. When harvest begins, berries must be picked every second or third day. Strawberries do not improve in sugar content or flavor after harvest. Postharvest Cooling One of the biggest problems in maintaining quality in fruit comes after the fruit is harvested.