Grab a stalk of Celery, lop off the bottom and leaves (which you can still use for soup stock, or freeze them until you have enough to make soup stock), and give it a good wash. Cut it into pieces about .5cm wide (1/4 inch) and drop them onto the dehydrator trays. You can blanch them, but I didn't bother, although it does stop it from turning a brownish colour. Celery shrinks a considerable amount, so keep your eye on them that they don't fall through the mesh trays (or add a solid tray between your layers).
Dehydrate for 6 to 8 hours at 55ºC (130ºF).
Dehydrated Celery is handy for soups.