What is the Difference Between Compost and Mulch

Difference between composting mulching

Mulch and compost are not synonymous. Simply put, mulch is applied to the top layer of soil to help control weeds, retain moisture, and regulate temperature, whereas compost is applied beneath the top layer of soil to benefit the soil by providing essential nutrients.

What is Compost?

what is compost

Composting is an aerobic process that converts organic ingredients into nutrient-rich soil amendments through natural decomposition. Composting accelerates the decomposition process by creating an ideal environment for bacteria, fungi, and other decomposing organisms to do what they do, which in this case is act as a catalyst. Compost, or organic matter, is the end result of decomposition and is dark brown with an earthy scent. Humus is essential for soil fertility.

Pros of Composting

Cons of Composting

What is Mulch?

what is mulch

Mulch is any material used to cover the soil’s surface. While all compost is made up of organic material by definition, not all mulch is. Wood chips or shavings, hardwood, and softwood bark are the most common types of mulch sold in bulk or bags at garden centers. Mulch can be made of many things, and there are also mulches that do not decompose and end up contaminating the environment, so always try to choose organic.



When to Use Which?

Your goal will determine whether you use compost or mulch. Both are beneficial for different reasons, but ideally, you should compost and mulch your garden beds with as much of your yard waste and kitchen scraps as possible.


If your primary goal is to enrich the soil by adding nutrients and improving its texture, work mature compost into the into the top few inches of your garden soil. Compost is usually used when it has broken down to a consistency the same as soil. It improves a soil’s structure and increases the availability of existing nutrients. Compost can be used to amend a given soil by mixing it in with the existing soil or by spreading it on top and allowing it to leach down through the soil profile over time.


If your main concern is to keep the weeds down and cut down on irrigation, apply mulch, preferably one that decomposes over time, so you get the added benefit of improving your soil.

Mulch is used to suppress weed growth, moderate soil temperature, conserve water, prevent soil erosion, and can decompose over time (eventually becoming compost) if made of organic material. Mulch is applied on top of the soil as opposed to being mixed in.

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