What is the difference between compost and mulch?

Sometimes we use the terms compost and mulch interchangeably which may create some confusion about what makes them different from each other.  While compost might be used as mulch, both have distinct functions and purposes in your garden.

In short, compost is an organic soil amendment made up of fully decomposed materials. Gardeners mix compost into soil or side-dress plants with it throughout the season to improve soil structure and water retention or drainage.  Compost introduces a diversity of microbes that help make nutrients available to roots.

Mulch can be organic materials or inorganic materials that gardeners spread on top of the soil.  Mulch will limit weed growth, reduce erosion, moderate soil temperature and decrease moisture evaporation. Some common types of mulch include wood chips, pine bark, buckwheat hulls, gravel, straw or pine needles.

Read our more detailed article about compost as well.