There are numerous reasons why not to use dyed mulches in the landscape. Aside from looking artificial here are a few more.
Origin of Dyed Mulch
Dyed mulches (black, red, green and other colors) are usually made up of recycled wood waste. This trash wood can come from old hardwood pallets, old decking, demolished buildings or worse yet pressure treated CCA lumber. CCA stands for Chromium, Copper and Arsenic; chemicals used to preserve wood. This ground up trash wood is then sprayed with a tinted stain to cover up inconsistencies in the wood and give it a uniform color.
Effect of Dyed Mulch
This dyed wood mulch does not break down to enrich the soil as good mulch should. Instead it leaches the dye along with the possible contaminants (chromium, copper, arsenic and others) into the soil harming or even killing beneficial soil bacteria, insects, earthworms and sometimes the plants themselves. These wood mulches actually rob the soil of nitrogen by out-competing the plants for the nitrogen they need for their own growth. Dr. Harry Hoitink, Professor Emeritus at Ohio State University, warms that dyed mulches are especially deadly when used around young plants and in newer landscapes.
What We Use
We at Naturescapes only use composted triple shredded back mulch. This product is 100% natural and organic that is naturally dark brown without additives. Shredded bark mulch breaks down over the course of a season or two to enrich the soil. It also increases the soil’s organic content, aids in beneficial soil bacteria and enhances earthworm production. Being composted, or naturally aged, it actually releases nitrogen into the soil therefore helping plants rather than harming them.