What is the difference between compost and mulch?

The terms compost and mulch are sometimes used interchangeably, which has created some confusion regarding the difference between the two. While compost is sometimes used as mulch, they are two different things that serve different purposes in your garden.

The basic answer to this gardening question is that compost is an organic soil amendment made up of decomposed organic materials. Gardeners mix compost into soil or side dress plants with it throughout the season to add nutrients to the soil and improve soil structure.

Mulch is most often used to describe organic materials but can describe either organic or inorganic materials that are spread on top of the soil to limit weed growth, reduce erosion, moderate soil temperature and improve moisture retention, i.e. sheet mulch. Some common types of mulch include wood chips, gravel, straw or pine needles. In lawn care, mulching can simply mean leaving the chopped grass clippings on your lawn to decompose and naturally return nutrients to the soil.