Melondy Phillips
Staff Writer
Mulch is a very useful additive to many gardens and landscapes. It holds in moisture, prevents weeds and gives an aesthetic look and feel. Some mulch is even beneficial for the soil and plants, adding nutrients to the soil as it decomposes.
The two main types of mulch are organic and inorganic. Organic mulch decomposes and can enrich the soil; made up of wood chips, straw, shredded paper, grass clippings and leaves. Inorganic mulches do not break down in a timely manner; such as gravel, rubber mulch, landscape fabric and plastic.
Wood chip mulch comes in a variety of choices. The old standard for wood chip mulch was shredded or chipped hardwood from sawmills for most of the garden, and shredded pine for acid lovers such as blueberries, azaleas and hydrangeas.
Over the past several years, I have had a more difficult time trying to find mulch near us that has not been dyed.
Dyed mulch has become a popular choice for landscaping due to its uniform color with several options to choose from. Dyed mulch allows you to color coordinate landscaping with the color scheme of the home, or just being able to choose a favorite color. Mixing and matching multiple colors within a gardenscape allows for personal creativity.
But what is dyed mulch doing to our soil?
Dyed mulch is often made up of recycled items including old pallets, old decking, and discarded construction debris. These recycled wood materials are inconsistent in color. Some of the recycled wood may have been treated with chemicals such as creosote or CCA (chromated copper arsenate). The dye helps to cover inconsistencies in color and evidence of chemical treatment, but it does not remove the chemicals. This has raised some concerns about the safety or toxicity of what is soaking into the soil around our homes, well water and food gardens.
When using dyed mulch for landscaping, the chemicals used may not seem to be much of a concern, unless you value the micro biome in the local soil. The dyes and chemicals soaked into the recycled wood chips leach into the soil, affecting beneficial bacteria, insects, earthworms, etc.
An article posted by the University of Florida in May 2019 reads, “Even though arsenic-based wood preservatives were banned in 2003, there are still plenty of CCA preserved wood being re-purposed. Sometimes wood pallets that have been used in the transport of chemical agents can become contaminated by spills of these chemicals. CCA and other toxic chemicals have been found to be contaminating soil where colored mulch made from these wood products have been applied. CCA treated wood can kill beneficial soil bacteria, beneficial insects, earthworms and young plants. It can also be harmful to people spreading this mulch and animals who dig in it.”
When deciding what mulch to use, start by assuming that all dyed mulch is contaminated with CCA repurposed wood. From there, check out the manufacturer and look for the MSC Certification Logo (Mulch and Soil Council) when selecting dyed mulch. The MSC is a non-profit association founded in 1972 and states that “the purpose of the certification program is to provide retailers and consumers with a means of determining which products conform to industry-accepted labeling and nomenclature.” Products that receive the MSC Certification Logo must conform to proper labeling requirements, pass laboratory testing, pass greenhouse growth testing (soils) and chemical testing for CCA-treated wood contaminants (mulches), and pass random audit testing in retail markets.
While dyed mulches are very popular, consider natural wood mulch. The natural color variations in non-dyed mulch add character and life to a garden or landscape. Everything in nature has variations in color that add to the “spice of life,” including leaves, insects and even human hair.
Wood chips are a natural part of an ecosystem. When a tree dies in the forest and falls to the ground, it begins to decay. The decaying tree adds food and nutrients to the soil around it, feeding micro-organisms and giving life for new plants to spring up.
There are several different techniques online that simulate the healthy growth of a forest floor. Mulches are an intricate part to these no dig natural gardens. Wood chips, leaves, straw and grass clippings are all beneficial for the health of a garden.
