March 2007
Getting to Know Mulch By Meghan Boyer

When it comes to mulch, many consumers know the term but don’t know exactly how to use the product in their gardens. They may not even realize how beneficial it is or the different options that are available. It’s up to you to teach them the dos and don’ts of mulch, starting with a break down of the two basic mulch types (organic and inorganic) and the options each includes.


Organic mulches are created from natural substances, such as lawn clippings, bark or leaves. They release nutrients and organic matter into the soil as they decompose over time and attract wildlife, such as insects, worms and birds. Consumers will need to reapply organic mulch as needed to maintain a proper mulch depth in their yards.

There are a number of organic options your customers can choose from, each with its benefits and challenges. Here is an overview of some common organic mulches:

Leaves and grass. Some consumers may want to use their own yard waste as mulch, which they can do in moderation. Extension agents at Clemson University found leaves provide good weed control. They recommend shredding leaves before applying them as mulch. Shredded material doesn’t blow away as easily and has better water penetration. Consumers can also leave grass clippings on the lawn to add nutrients back into the soil. Advise your consumers on how to properly prepare their yard waste and make sure they know to avoid material that has been exposed to chemicals, such as herbicides.

Wood chips. Long-lasting and attractive, wood chips contain pieces of bark and wood in various sizes and provide good weed control. As the chips decompose, they use nitrogen from the soil, which can be replaced with a nitrogen fertilizer. Woods chips may attract termites and other insects.

Pine bark. A dark-colored mulch, pine bark also provides weed control. Sizes range from shredded to large particles, called nuggets. Erv Evans, a horticulturalist with North Carolina State University, notes that pine bark mulch is primarily used as a soil conditioner and pine bark nuggets are used as mulch. When used as mulch, the bark should contain less than 10-percent wood fiber, according to Evans. Large nuggets float in water and may wash away in heavy rains, and pine bark may attract termites and other insects.

Other materials. There are many organic materials that are sometimes used as mulch, including wheat straw, shredded newspaper, peanut hulls, pecan shells, sawdust and even cocoa bean shells. Make sure customers are aware of each option’s benefits and limitations. For instance, light-colored, fresh mulch will generally tie up nitrogen in the early stages of decomposition, thereby removing it from plant use. The more customers know, the better they will be able to choose an organic mulch for their yards.


Inorganic mulches, such as landscape fabrics, pebbles or gravel, and black plastic, do not decompose or attract pests. Some options, such as stone mulches, are permanent, which makes them well suited for permanent landscape plantings. Here is an overview of some common inorganic mulches:

Stone options. Gravel, pebbles, rock and more are permanent mulch options for consumers who want weed control. Consideration should be given to which plants and garden types are paired with stone mulches. According to Clemson University extension agents, some rocks may add alkaline elements and minerals to soil. Additionally, light-colored rocks reflect sunlight, causing plant temperatures to rise. Rocks also absorb heat during the day and release it at night, which contributes to increased water loss.

Fabrics. Landscape fabrics prevent most weed growth, though some grasses may grow through, and allow water and oxygen exchanges. Make sure consumers know to fasten down the fabric to prevent weeds from pushing up. Evans recommends covering the landscape fabric with organic material for better results; the decomposing mulch creates a layer in which weeds can grow.

Black plastic. While black plastic is effective in preventing weed control, it does not allow water, nutrients or air to move through it. Because of this, plants can develop shallow root systems or incur root disease problems from overly wet soil. For consumers who desire the control of plastic but do not care for its look in the landscape, recommend covering the plastic with a layer of wood chips; it can help mask the plastic’s appearance and reduce heat absorption.

Other materials. New types of inorganic mulch are still being developed. One of the newer options is rubber mulch, which is sometimes made out of ground tires.

Send Tips Home

Don’t assume your consumers will know how to apply their mulch once it arrives at their homes. Consider printing up instructions that you can give to consumers who purchase mulch. The instructions can include application tips, problems to watch for and upkeep instructions (such as installing a border to help keep stone mulch from rolling out of place).

Make sure you warn against using too much mulch: A layer of mulch that is too thick can cause plant roots to grow in the mulch and not in the actual soil. On the other hand, a layer of mulch that is too thin does not yield all the expected benefits.

With your help and tutelage, your customers will become well-versed in the best types of mulch for their applications, which can lead to increased (and even repeat) mulch sales for you!

Meghan Boyer

Meghan Boyer is associate editor of Lawn & Garden Retailer. She can be reached at [email protected] or (847) 391-1013.