The amount of bags of mulch in a yard depends on the size of the bag. If the bags contain 2-cubic-feet of mulch, then 13.5 bags are needed to fill one yard. Nine bags are needed if using 3-cubic-feet bags.
Mulch is any type of organic material that is spread or laid over the surface of the soil as a covering. It is generally used to prevent weeds, retain moisture and provide an ongoing supply of nutrients to the soil. Mulch varies in content and density, and the denser mulch may not cover as wide of an area as a lighter mulch (such as straw).