A buckwheat pillow is easy to care for as long as you keep the hulls dry. Normal moisture from sleep such as sweat or drool is perfectly fine. The cotton case can be washed whenever you want to freshen it up, but don't soak the hulls because they may not dry completely.
To clean the fabric, empty all of the hulls into a container first. I like to use a paper bag. Avoid plastic bags because the hulls get quite jumpy with static!
Wash the cotton case in cold or warm water with mild detergent. Hang it to dry or tumble dry on low heat. Once the case is fully dry, refill it with the hulls.
Do not wash the buckwheat hulls. If they get wet, they can hold moisture inside and may never dry out. Keeping the hulls dry is the most important part of maintaining your pillow.
You can freshen the hulls by placing them in the sun. Spread them out in a shallow layer and let them sit in direct sunlight for three to four hours once or twice a year. This helps remove any moisture and keeps the hulls feeling crisp. It works best to spread them out but you can do this when they're in the pillow and fluff up the pillow from time to time to circulate the hulls.
Over time, the hulls become polished with use. This is normal and actually good for them, but it does reduce the overall volume of the pillow. After a year or two, you may want to add a small amount of fresh hulls to restore the height.
Most people only need to top up their pillow once. The hulls last for many years, and a small refill is usually enough to bring the pillow back to its original comfort.