To clean the fabric, first empty all of the hulls into a container. Wash the fabric in cold or warm water with mild detergent, hang dry or tumble dry on low heat. DO NOT wash the buckwheat hulls, as they may never dry out. Alternatively, you can place the pillow in direct sunlight for 3-4 hours once or twice a year.
To freshen the hulls, empty the pillow and spread the hulls out in the sunlight for 3-4 hours once or twice a year.
After a year or two, the buckwheat hulls will become polished with use. This is good for them, but the pillow will be lower in volume than when you first received it. Around this time, you will want to add some hulls to your pillow. You will only need to do this once.