Help Me Teach Landscapers Not to Use Dyed Mulch

There isn’t a quality full-service landscaper in Houston that uses dyed mulch in their projects. Sadly, that means there are scores of landscape companies that apparently don’t care about quality. Landscapers who keep using dyed mulches are either …

Just in it for the money and deny science.

Are absolutely uneducated and couldn’t care less about learning the facts.

In both cases, they simply disregard how toxic dyed mulches are to soil. So, I’m reissuing this piece, originally posted on Facebook, to help teach landscapers willing to learn and homeowners willing to share this info with their landscaper. Bottom line, this is what every landscaper should be telling their customers who ask for “dark-colored” mulches.

At a 2019 Christmas party, these teaching points came to me in a spirited discussion with a professional landscaper who was trying to convince me that it’s okay to use dyed mulches. He started off claiming he is just doing what his customers want when they ask for dyed mulch. That’s when I gave him a list of things he should tell those clients. 

As I reeled them off, he wrote them down. Then, as he reviewed the list, a revealing look washed across his face and at that point, I knew I had converted him to Texas-native or naturally shredded mulch.  Or even to the idea of using compost in place of mulch. And I also knew I had to share it with everyone. So, here’s the list I gave him:

Dyed mulch doesn’t look natural: It looks artificial, and as anyone with solid horticultural experience will attest, it’s the equivalent of putting plastic flowers in a landscape – something most people would make fun of. Mulch in a landscape should be part of nature, reflecting a natural aspect. Plus, when yellowing or brown leaves fall onto black mulch, they stand out rather than blending in as they would with a natural-looking mulch.

Most dyed mulches are made of recycled waste wood: It’s almost always composed of “trash wood” that comes from pallets, old decking, demolished buildings or – even worse – treated CCA lumber. CCA stands for chromium, copper, and arsenic – chemicals used to preserve the wood. Once ground up, the wood is sprayed with a dye to cover up inconsistencies and give it a uniform color. Most dyed mulch manufacturers claim their dyes are “organic,” but are rarely open about their source of wood material.

There’s a negative effect on the soil: Dyed mulch doesn’t break down into the soil the way native mulches and shredded mulches do. Instead, dyed mulches, especially those midnight-black styles, leach dye and possible CCA contaminants into the soil, killing beneficial bacteria. It kills off beneficial insects and earthworms, too. The dye runs off the piles after a simple rain. It’s doing that in landscape beds, too!

Nitrogen starvation almost always happens: When you see yellowing leaves on annuals and perennials, nitrogen present in the soil is working so hard to break down the wood that roots aren’t getting anything to help the plants green up.

Shredded native mulches with composted elements break down in the soil: The best mulches become part of the soil’s organic content over time. That makes for more beneficial soil bacteria and enhances the environment for earthworm production. Composted mulches or naturally aged versions actually release nitrogen to the soil, thereby helping the plants rather than robbing from them.

For those who say, “this is the only mulch my landscaper will ever use,” print a copy of these points and hand it to them. If they balk, get a new landscaper. That’s about the easiest change to make in this whole debate.