Place the blueberries evenly on the dehydrator racks. My Excalibur Dehydrator said to set the temperature at 135 degrees. Please check your unit for the correct temperature. The time to dry the blueberries will depend on the humidity of the room you are drying your blueberries in. Plan on 12-23 hours. Dehydrate until the blueberries are leathery and crisp. When totally dry use your high power blender to make powder by using the pulse button. Store the dehydrated blueberries or blueberry powder in airtight jars.