Fill a bucket with 1 gallon of hot water. Add 3-½ cups of household bleach and 1 oz. of liquid dish detergent to the gallon of hot water and stir thoroughly to make sure they are mixed together.
Soak a rag, sponge or soft-bristle scrub brush in the detergent mixture. Clean the cedar surface with this mixture. The bleach will kill any mold spores that have congregated on the surface. This mixture will also remove any layers of dirt or dust, revealing the true cedar color underneath.
Wash the wood once every six months or as needed to remove surface dirt and dust. The actual cleaning needs will vary, depending on how heavily the the cedar item is used.
Apply a thin layer of linseed oil to the cedar after cleaning. Work it into the surface with a polishing cloth or lint-free cloth; always work in the direction of the grain. This will enhance the natural look of the cedar and bring out the grain, and will also provide a thin layer of protection for the wood.