To properly freeze blueberries, place dry, unwashed blueberries in a plastic bag or in their original container, and put them in the freezer. Fresh berries work best with this method.
To prepare blueberries for freezing, sort them, and remove any spoiled berries, leaves or twigs. Do not rinse or wash them, as this toughens their skins. To freeze blueberries individually, spread them on a tray, and transfer them to a container after they freeze.
If crushing or pureeing blueberries, add 1 cup of sugar for each 2 pounds of blueberries. Stir until the sugar dissolves, and pour into containers, leaving a space at the top of the container. Use frozen blueberries within six months.