Coast of Maine Organic Products Dark Harbor Blend Enriching Mulch is an exceptionally rich, naturally dark, fine textured blend of self-composted barks.  It helps retain moisture and insulate the surface soil against temperature variations that can harm roots. Because it is composted, it will not rob the soil of nitrogen and can be dug into the beds in the fall to improve the organic content of the soil.  Available in 1 & 2 cu.ft. bags.