The exact window of time during which a berry is ripe and ready to be harvested depends heavily on soil and atmospheric and climate conditions in the area wherre the berries are being grown. Thus, it is very difficult to give exact instructions on how and when to pick blueberries. The best option is always to consult a local agricultural expert, particular one with experience in growing wild berries, as to the ideal time to pick your blueberries.
Blueberries turn a deep blue color and grow to the size that you would see them in a grocery store when they are ripe and ready to be harvested. They appear plump and full with no traces of red. Note that different clusters ripen at different rates, so do not be alarmed if not all of the blueberries reach ripeness at the same time.
As noted, blueberries can be pulled away from the clusters with gentle pressure from the hand when they are fully ripe. Remove all leaves, stems, and other greenery from the berry. To test the ripeness of the blueberry cluster, gently tug on one of the berries to see if it easily comes loose. Some growers prefer to leave the blueberries on the vine for a few more days to develop the flavor.
Remove all excess leaves, stems, and greenery from the berries and store them in a small, porous container. If they are to be used on the same day as they have been picked, berries can be kept at room temperature. Storing the blueberries in the refrigerator extends their life to 10 to 14 days. You can also freeze blueberries and thaw them when ready for use. Avoid washing the berries until just before you eat them to maintain their consistency.