Why Dyed Mulch is Ecologically Problematic

It’s not your imagination that dyed mulch is covering your neighborhood. It's been around for 60 years, but the dyed mulch market has skyrocketed in growth in the last 20 years. One source indicates that from 2009 to 2018 it grew by 72%. This was before the pandemic when the overall mulch market really exploded. It has leveled off since then, but the North American mulching material market is still trending – it’s forecast to be $850 million dollars in 2024.

A better term for dyed mulch might be sausage mulch because you don’t know what’s in it and you don’t want to know how it’s made! When talking about how safe dyed mulch is for the ecosystem, most studies tend to focus narrowly on the dye itself which is often not toxic.

The old adage about you not wanting to know the dirty details about how sausage is made applies to both sausage and dyed mulch!

Yet if you read a bit more carefully, these studies note that the wood in the dyed mulch could be toxic. This is because most dyed mulch is made from recycled scrap wood. The scrap wood used is called construction and demolition (C&D) waste which is broadly defined as materials used in buildings, roads, and bridges. It’s not normal consumer trash.

Demolition waste like these sidewalk chunks don't end up in the trash bin, they go to a landfills or become C&D waste.

About 40% of all materials at the mixed C&D recycling facilities are wood waste. The wood waste can come from building construction and demolition; wooden crates; pallets; furniture manufacturing; landscaping; lumber mills; and trees and branches from land clearing.

This is the kind of scrap wood that ends up being ground up, dyed to look "natural", and resold as mulch.

The common term “next use” of this debris designates an intended next-use market which for wood products includes compost, soil amendment, soil, or mulch. The industry itself suggests that the biggest limitation to secondary use of wood waste is a limited marketplace due to inherently high contamination level associate with reclaimed wood. The high percentage of wood products that aren't reusable account for almost 10% of all material sent to landfills each year. The maze of ways the wood could be contaminated is eye opening.

• Some of the wood from C&D waste is contaminated with a group of pesticides called Chromated Arsenicals (CCA) which according to the U.S. Environmental Protection Agency could have chromium, copper, and arsenic in them. CCA has not been used on wood since 2003, but C&D waste includes repurposed wood that could easily be from before this date. The Mulch & Soil Council (MSC) has a voluntary MSC Certification Logo certifying that mulch or soil is free of CCA-treated wood. Two problems with this: 1) most folks don’t even know this certification exists and 2) not all mulch products even have this certification, so the consumer would need to know to check for this certification on the package. (Other issues with this certification are noted within some of the points made below)

I'm a fairly aware consumer and just learned about the MSC certification logo and how many products are classified as "mulch".! When I checked at a big box hardware store not all the "mulch products" had this certification.

• Wooden pallets that end up as C&D waste may not have been contaminated with CCA but are troublesome in several other ways:

1. They are unsustainable! Pallets contribute to 1 million acres of trees being destroyed worldwide every year and at any given point there are 2 BILLION pallets in use in the United States. Unfortunately, they are often not even reused - 54% of wood pallets are only used once so a percentage of them are used as C&D second market.

2. Some pallets may have been used in the transport of chemical agents that could have spilled and contaminated them or they may have been treated with pesticides. Pallets that have been treated in any way have some sort of stamp on them which might help if you're doing a DIY pallet project, but the C&D waste pallets are all ground up together.

3. The National Consumers League studies showed that  10% of pallets tested positive for E. coli and 3% Listeria bacteria. In those same tests, almost a third of pallets had high aerobic plate counts indicating unsanitary conditions where bacteria can easily grow. I'm not sure how this might impact them in second use, but it's an indication how filthy they are!

4. Woodworkers are extra cautious when using pallets because of the possibility of chemicals on them plus the wood dust is a known carcinogen.   (Much of the information about pallets was from the Circular Supply Chains website.)

Grinding up pallets and selling them as mulch is indicative of what a problem pallet waste is, not a solution to it.

• To make things even more complicated and worrisome with dyed mulch, even though the MSC Certification Logo means the mulch product is free of CCA pesticides, it explicitly excludes the possibility that C&D mulch products are pesticide free from other sources! This also means that the bagged mulch, compost, soil amendments, and soil from the garden center might be contaminated with pesticides. I checked and sure enough, even the organic potting soil I so virtuously buy for all the native plants I give away has a fine print disclaimer excluding it from documenting possible pesticides from C&D waste that might be in the bagged soil. There's even a category for "premium pottig soil" which my organic potting soil falls in. Mulch made from green waste such as scrap wood or the lumber industry also might have pesticides because they are used in the lumber industry.

My heart sank a little when I realized the organic potting soil I use could possibly be contaminated with pesticides - it doesn't matter if it's in the "premium" category. Pesticides are like plastics and are becoming impossible to escape.

For now, I need to make semi-peace with the reality of the container soil I’m buying because the bigger picture is that I’m giving the plants to nature friendly folks who will be putting them in chemical-free yards where they’ll be providing habitat for wildlife.

I know the hundreds of plants I give away each year will create habitat where they grow - like this tray I gave to someone who had the City of Atlanta mow down his rewilded right-of-way strip. I don't give soil from my yard so I need to find a source other than bagged soil!

I need to find a safer, local source for an organic potting soil. if possible. The best option would be to start hot composting in my own yard which creates compost faster. I use the passive cold composting approach that takes a year or two. I have shoulder issues, so the hot composting isn’t realistic or I’d be on it!

I can't physically turn compost so I do the definition of cold (lazy) composting - waste goes into this bin I got from my neighborhood Buy Nothing group and rarely comes out!

•  Dyed mulch doesn’t decompose the way regular wood would. The added possibility that dyed mulch made from C&D waste is made of wood that was treated to not decompose and add anything but the possibility of chemicals back to the earth is a reality. The marketing for dyed mulch often claims it's long lasting.

Dyed mulch ultimately ends up a distinctly unappealing grey once the dye fades and the mulch looks more like ground up bits of scrap wood that never seem to decompose!

• The C&D waste wood is dyed after it’s ground up to even out the way it looks because it’s not as uniform as natural wood chips might be. If there are CCA or other toxic chemicals in dyed mulch, they can contaminate the soil, leach into the water, and affect the food web. For example, earthworms are not toxic, but any toxins they get from ingesting the soil and the microorganisms from the soil would be in the worms’ tissues or on the worm itself - and any creature that preys on the earthworm if it doesn’t die from the toxins! About 15-20% of a robin's diet come from earthworms. It would be tragic if the robin below who is making a nest with grass clippings feeds her babies earthworms she gets from contaminated mulch. It's a possibility around me where so many homes use this stuff.
  

Dyed mulch that is contaminated with any kind of toxin could also impact wildlife or the pets and people who come in contact with it or track it inside the home. I also wonder about all that dyed mulch covering so many public and home playgrounds. When my grown son was young, he was the definition of an experiential learner, and everything had to be touched and often ended up in his mouth. How many young children are not only playing on that mulch but exploring the mulch itself?!

I'm glad dyed mulch was not yet popular when my son was little or those big red chunks of dyed mulch would have gone right in his mouth!

Aside from the possibility of dyed mulch being toxic in some way and despite the intent to repurpose waste, the processing, packaging, and shipping of dyed mulch has a large carbon footprint.

Pallets of processed and dyed mulch in plastic bags are unsustainable at every step of the process.

The good news is the idea of “mulch beds” with lonely plants separated by artificially colored mulch comes from the old school ornamental gardening culture that has no functional purpose in all the sustainable and ecologically driven landscapes popping up. The issue of HOA rules and mulch beds is a prime example of the havoc HOAs are wreaking on local ecosystems just to maintain an outdated aesthetic - which leaves homeowners with limited options. This is also slowly changing.

I don't speak HOA, but know the rules need to change to help homeowners create more ecologically safe outside spaces. The ornamental landscape with dyed mulch "look" is outdated and does nothing to support the local ecosystem.

The new vision for a more sustainable living landscape doesn’t have a place for the buying plastic bags filled with the wood equivalent of plastic plants. In an ecological landscape, the bragging rights include what life the habitat supports.

Having a yard that is a source of life is the new trend and I'm all for it!

I haven’t bought bagged mulch in 15 years because the function that the mulch offers is done by the natural systems in place in my yard. The two top processes are:

Native Plants as a Living or Green Mulch : If you use dense native plant communities in the same way you would use mulch you get more benefits than mulch. Native plant communities can enrich and protect the soil, naturally suppress weeds, enrich biodiversity, create and connect fragmented habitat, and control erosion.

Throughout the year there is no room for dyed mulch or any other kind of mulch in my small rewilded yard. The dense and layered native plant communities are doing all the work beautifully!

Leaving the Leaves: Leaves offer the same ecosystem service as a living mulch of native plants does in places where dense planting might not be viable, such as under a tree where leaves are meant to be. Mow and blow crews blowing leaves from under trees then dumping bags of dyed mulch in their place is destructive make-work.

Leaving the leaves offers the mulch benefits needed where nature doesn't see a need for many plants, such as under oak trees.

What we don't do in our yards is often just as important as what we do. Not buying sausage mulch is an easier way to nurture a healthier outside space for all living things - it's also more sustainable, less expensive, and not as labor intensive.

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