When you buy fresh blueberries, look for berries that are firm, dry, plump and smooth-skinned, with a silvery surface bloom and no leaves or stems. Size isn’t an indicator of maturity but color is – berries should be deep purple-blue to blue-black.
Refrigerate fresh blueberries when you get them home, either in their original plastic pack or in a covered bowl or container. Be sure to wash your blueberries just before you start snacking, and eat them within 10 days of purchase.
* This is off the U.S. Highbush Blueberry Council website