Look for grapes even in color and attached to the stem
The grapes should be plump and firmly attached to the stem. Look at their color: The tones should be even. The green grapes should have a yellowish hue, while the purple grapes should be a robust purple with no greenish tinge.
Refrigerate grapes in the bag they came in
Don’t wash grapes when you get them home. Store them in the refrigerator, in the bag they came in. They should last three to five days.