Can Mulch Be Used As Compost?

At Hawkins Landscape Supply, we understand that gardeners and landscapers are constantly looking for ways to optimize their outdoor spaces. One common question we encounter is whether mulch can be used as compost. While both mulch and compost play significant roles in gardening, they serve distinct purposes and are not generally interchangeable. Here’s an in-depth look at why mulch cannot be used as compost, among other related insights.

The Specific Purpose of Compost

Compost is essentially decomposed organic matter that enriches the soil by improving its structure, moisture retention, and nutrient content. It is created from a mixture of ingredients such as kitchen scraps, yard clippings, and other biodegradable materials, which break down over time through microbial activity. The end product is a rich, earthy material that is excellent for amending garden soil.

Mulch, on the other hand, does not suit this purpose because it is typically made from materials that decompose slowly, such as wood chips, straw, or rubber. These materials are used primarily to cover the soil surface, not to enrich it directly. If used as compost, mulch would not break down quickly enough to provide the immediate nutrients that plants require from compost.

The Purpose of Mulch

Mulch suppresses weeds, retains soil moisture, and regulates soil temperature. It acts as a protective barrier for the soil, keeping it cool during the summer and warm during the winter. Unlike compost, mixed into the soil to improve its properties, mulch is laid on top of the soil around plants, paths, and beds.

When Compost Can Act as Mulch

Interestingly, the converse is true: Compost can be used as mulch. If spread on top of the soil, compost can provide a moderate barrier against weeds and help the soil retain moisture, much like traditional mulch. However, because compost is rich in nutrients, it also continues to feed the soil and plants, which mulch does not primarily aim to do.

Instances Where Compost Might Not Work as Mulch

While compost has many benefits, it might not always be the best mulch substitute, particularly for plants requiring specific soil conditions. For example, plants that thrive in alkaline soils, such as blueberries, might not benefit from compost used as mulch if the compost significantly lowers the pH of the soil.

Incorporating Mulch into Compost

Old mulch can indeed be incorporated into compost piles. Adding mulch to a compost bin can be a great way to recycle it as you replace mulch in your garden. However, it’s important to note that mulch will decompose slower than typical compost materials. As it breaks down, wood-based mulch will gradually contribute carbon to the compost, vital for balancing nitrogen-rich materials like food scraps and green yard waste.

In conclusion, while mulch and compost are essential for healthy gardens, they should be used according to their specific purposes to achieve the best results. At Hawkins Landscape Supply, we recommend using each material appropriately to enhance the beauty and productivity of your garden spaces. Remember, while mulch cannot substitute for compost, incorporating it into your compost pile can enhance your composting efforts.

Learn More:

How to Get Started Composting