Make the most of mulch by choosing from living, synthetic, inorganic, or organic

Mary Fischer

URBANA, ILLINOIS

Every spring, gardeners turn to mulches for their landscapes and gardens for a variety of reasons. One of the main benefits of mulch is reduced soil erosion and compaction. Mulch also moderates soil temperature keeping it warmer in the winter and cooler in the summer. Another benefit is reducing weeds which can help reduce pesticide use.

While the different mulch types have similar benefits, each type of mulch has some things to consider when choosing the best fit for a garden or landscape.

There are four different types of mulch used in landscapes and gardens – living, synthetic, inorganic, and organic. By considering the pros and cons of each type of mulch, you can choose the best mulch for your garden or landscape.

Living Mulches

Living mulches include ground cover or cover crops. Synthetic mulches would be any materials created by people. Inorganic mulches are materials such as stone, tumbled glass, or concrete pavers. Organic mulch is a broad group of materials with different amounts of processing that will decompose over time.

Living mulches such as ground covers can compete with water, light, nutrients, and space resources. In a space where these resources are limited, especially water, a non-living mulch would be a better choice. 

Synthetic Mulches

Recycled rubber mats and chips are typical examples of synthetic mulch. This mulch will break down slowly, so it doesn’t need to be replaced as frequently. Eventually, it does decompose, which can release some chemical components that are not desirable for healthy soil. 

Landscape fabrics are also considered synthetic mulch. Seasonal weed control is one of the most common uses for landscape fabrics or sheets of plastic. This mulch can restrict water and air movement between the soil at the atmosphere, which can cause negative effects on plants and soil organisms. Because of these potential negative effects, landscape fabric is not ideal for long-term use in a specific location.

Inorganic Mulches

Inorganic mulches, like stone, weather slowly making them long-lasting. Research shows that rock mulch doesn’t increase soil temperatures in the summer. While deep stone mulch can provide weed control in the short term, it is not permanent. Weed seeds and soil blow in, resulting in a weed population that can be difficult to control without herbicides. 

Organic Mulches

Organic mulch such as sawdust, compost, wood chips, and nut shells will decompose in a relatively short time. That means it will need to be replaced more frequently than other mulches. 

Sawdust and compost can be used in deep layers to control weeds. Because of the fine texture, gas and water exchange can be decreased. Sawdust can tie up certain nutrients as it begins to decompose, meaning that the soil nutrients are not available to plants.

Wood chips, bark, and nutshells are coarser, which allows better air and water exchange. As these break down, some nutrients are added to the soil. Wood chips are better at absorbing and retaining water than bark and nutshells.

Research shows that arborist's wood chips provide more benefits with fewer drawbacks than other mulch choices. Due to their wide availability, wood chips are a cost-effective mulch for many different locations.

For more research-based information on landscaping, connect with your local Illinois Extension county office at go.illinois.edu/ExtensionOffice. Download an infosheet about mulches. ∆

Mary Fischer: University of Illinois