Colored Mulch: the Good, the Bad, and the Ugly

A pair of hands reaching into a pile of mulch and holding a handful.
What You'll Need
Clothes for covering exposed skin

Many homeowners use colored mulch in their landscaping and gardening. Popular options like red mulch and black mulch not only provide the horticultural benefits of mulch, but also give your multicolored flowerbeds a decorative pop. Although, many critics cite the potential dangers, garish colors, and the unnatural look.

Regardless of color, mulch still serves a purpose, so to get the best results from any kind of mulching routine, provide a 2-3 inch layer to your garden in the spring for water retention and again in the fall for winter protection.

While using colored mulch is a personal choice, there are some things you should consider before choosing red or black mulch.

Why Do Some People Favor Colored Mulch?


This is the number one reason to even consider colored mulch. In terms of its utility, colored mulch is essentially identical to regular mulch, but people find the shock of red or black color attractive and enjoy the way it complements their existing plants and landscape. Since one of the basic goals in both gardening and landscaping is to create a space that looks appealing, it isn't hard to see why many homeowners would choose the stark contrasts of red and black mulch.

Claims of Improved Mulching

While it’s yet to be proven in a controlled setting, many gardeners claim that the specific colors of their mulch do have an influence over the success of their planting. Colored mulch enthusiasts swear by red mulch for strawberries and tomatoes, claiming the color reflects more sun back toward the plants and encourages better growth.

Some gardeners also believe that black mulch keeps soil warmer, as black pigments absorb sunlight and heat rather than reflecting it as lighter colors tend to do. In situations where a plant would benefit from increased warmth at the soil level, black mulch would potentially have an advantage over other choices.

Why Do Others Condemn Colored Mulch?

Mulch Dye

The large scale manufacturers of colored mulch use iron oxide to dye their red mulch and carbon black for their black mulch. Both of these additives are non-toxic and safe to handle. Iron oxide is basically just rust, which isn’t harmful in the context of mulch, and carbon black is essentially the same residue you notice when handling burned charcoal.

The real controversy surrounding mulch dyes exists due to smaller, off-brand companies that use forms of dye that are considered toxic. These options are sometimes cheaper, so even while safer options exist with the bigger brands, thrifty and uninformed consumers still buy these colored mulches and leech those toxins into the environment, not to mention their own skin and lungs.

Treated Wood

CCA pressure-treated wood should never be used as mulch because one of the ingredients that makes up the CCA (chromated copper arsenate) is arsenic, a poisonous substance and carcinogen. It can leak through the surface of the wood. Even though this type of wood was phased out in 2003 by the EPA, mulch manufacturers that create their product from used wood, like old crates and pallets, are likely sampling from stocks of harmful, treated wood. This threat is much more prevalent than toxins from dye.

Choose mulch made by companies whose wood comes from raw lumber rather than recycled wood items to eliminate this risk.

Fading and Color Transfer

Colored mulch fades and has to be replaced more often than natural mulch. Another common problem is the color from the mulch dye transferring to your hands and arms as you spread it. You should always wear gloves and cover exposed skin while planting to minimize this exposure.

New mulch also hasn't "settled" yet, so you shouldn't walk across it or let it come into contact with anything that could be stained. Walking across the mulch will probably track the color, which may be difficult to remove from some surfaces.

It’s worth noting that no such precautions, risks, or expenses are necessary with regular mulch that isn’t colored.