Is Black The New Brown?

Mulch is always an interesting point of discussion as well as the topic of several past GP posts. But I honestly can’t recall if we’ve covered dyed mulch, and can’t search the site, so here goes.

I recently received a request for information from Debbie Dillon, a fine Urban Horticulturist with Virginia Cooperative Extension.  She noted the increased use of dyed mulch in the Northern Virginia area, and has been fielding questions from both landscape designers and homeowners regarding the safety of said mulch and the potential for harmful effects on plants. Black seems to be a fave color of late.

All I could offer her at the time was “Bleccch, I really don’t care for it” and a promise to investigate further. Armed with a bit of spare time and Google – here’s what [little] I’ve found out.

There are several products out there, such as Solarfast MCH and Mulch Magic. They’re used commercially on bulk mulch and are also available to the homeowner without restriction. From the Solarfast website – “Solarfast MCH is a colorant used to restore faded mulch back to its original color. It is environmentally friendly and does not contain hazardous chemicals, heavy metals or other ingredients that are known to be harmful to the environment.”

Is it safe?

The MSDS (Material Safety Data Sheet) for Solarfast was incomplete – it did not list components. The MSDS for Mulch Magic indicates the black contains carbon black, red contains iron oxide, and brown contains diethylene glycol monobutyl ether (as well as carbon black and iron oxide). The composition beyond that (carriers, surfactants, etc.), was not noted.  Diethylene glycol monobutyl ether is a fairly common solvent for paints and inks with purportedly low environmental toxicity, but can irritate skin and eyes. Carbon black can be made from various sources but is basically a petroleum product, used in laser printer and photocopier toner as well as the manufacture of reinforced rubber (i.e. tires).  Most concerns are related to worker inhalation at the point of manufacture. Iron oxide is, well, oxidized iron, and has been used as a pigment for quite a while (i.e. cave paintings at Lascaux, Bob Ross, etc.).

What about the plants?

There are many, many studies on pigmented film mulches (usually polyethylene) in fruit and vegetable production.  Certain colors can alter plant growth and processes, such as flowering and fruiting, stem length, etc., but I couldn’t find a thing regarding dyed, wood-product mulch. Issues of concern might be that the dye is disguising the composition of the mulch. Apparently dyes are frequently used on “pallet mulch” – shredded pallets, usually made from softwood. Another concern might be the increase in root-zone temperature, especially from the use of heat-absorbing black pigments. Could soil temperatures warm to the point of causing a too-early bud break?

Is it aesthetically pleasing?

Apparently “yes”, to some, because there’s a market for it. What do you think?

This photo was taken in April at a local medical center (it was a rainy morning, pardon the low light). The fairly typical commercial landscape surrounding the building is dotted with beds and trees freshly mulched in black. Note the classic mulch “volcano” in the background. No sir, I don’t like it. But that’s just me.

Toxicity information on compounds noted available at the International Agency for Research on Cancer (IARC) – Summaries &  Evaluations,

18 thoughts on “Is Black The New Brown?”

  1. Oh, those poor trees! The first thing I saw was the mulch ‘volcano.’ You really are changing the way I think. Thank you for the post!

  2. Re: the question whether warmer soil would cause earlier bud break: it won’t. Breakage and induction of bud dormancy is relatively localized and is a combination of relative daylength and air temperature. (But warmer soil temperatures will enhance root growth through the cold season…as mentioned in one of my comments on yesterday’s post. Roots never go truly dormant.)

  3. I really don’t like these false colors ! IMHO, mulches should meld with the surroundings, not jump out & bite
    you like these do. I don’t care for the additives that create the color either, even on non-food plants.

  4. While I prefer natural colored mulch, I appreciate the use of mulch in all its forms and varieties. Anything that promotes healthy plants while also reducing water usage is fine by me.
    Maybe black mulch would be a good idea for newly transplanted trees to re-grow lost roots due to transplantation?

  5. I disagree, I love when mulch stands out and gives a different visual. Although this is away from any standard practice I think it gives your garden individuality and certainly makes it stand out. I say stick with it!

  6. I have tried them all and have a few thoughts. I am in an exposed, sunny, windy McMansion development. I would really like to use leaves as mulch but they blow away. Un-dyed hardwood mulch looks TERRIBLE after a few weeks in bright sun. It becomes white. When used in a shady situation, un-dyed hardwood mulch looks nice. I wiped out a ton of grass with huge beds and it is taking a while to fill/grow-in with plants. Black mulch creates a nice backdrop for green plants. In fall I’ve been adding composted leaves under the mulch. It looks great. Also, I’ve recieved black muclch from a couple different places and I’m pretty sure that one of the products is chipped-up pallets and waste wood dyed black and that stuff is awful. From my local nursery, I get a finely shredded hardwood mulch, dyed black that smells like heaven when you dig-in! And my plants are growing fine….

  7. I’ve learned that aesthetics are really important in mulch choices. Many people want a uniform color for mulch, and arborist wood chips, etc. don’t cut it. My feeling is that if we can get more people to use organic mulches (rather than no mulch or *shudder* landscape fabric) then we’ve succeeded. If colored mulches help in doing this, I’m all for it.A couple of asides here: (1) you can save a lot of money on the colored mulches by putting a layer of wood chips down first, then covering with a layer of the colored stuff. (2) Be VERY careful in using chipped pallets as mulch. Many of them have been treated with pesticides and should NOT be used in your landscape.

  8. Thanks to the recent permaculture discussions I decided not to try cardboard sheet mulch and applied a 3-4 inch layer of UNDYED shredded hardwood mulch.

    Does the minimun disruption concept also apply to the mulch layer?

    (reformed double-digging, amendment-mixing,compulsive cultivator)

  9. @veggies&roses, can you clarify what you mean by “minimum disruption concept?” My brain is a bit damp with our Seattle weather today.

  10. Prof Chalker-Scott

    By ‘minimum disruption concept” i am refering to the “no-till” ideas that Lee Reich explained in his book “Weedless Gardening”. What I got from his book was that he acknowledged that it is difficult to NEVER disrupt the soil structure, and to therefore think in terms of minimizing disruptions to the soil structure.

    So to rephrase my question: Does “no-till” apply to the mulch layer also?

    Thank you.

  11. No-till is always good when feasible. In terms of the mulch layer, it’s much less cohesive than the underlying soil. That being said, if you disrupt it significantly you expose those fungal hyphae to light and desiccation and they die. So it’s best to just let it sit unless you’re planting, in which case you move it back before digging. Organic mulch is incredibly forgiving – much more so than soil.

  12. Just my opinion, but if people comment on “what a nice mulch job in your garden”, there is something significantly lacking in your landscape design…

  13. I agree with Brian – mulch shouldn’t be a component of the design. And now do we have to add ‘repaint the mulch’ to our list of spring chores? Is it just me, or is that completely nuts?

  14. While I philosophically agree with Brian and Carol, the reality is that many people only see their landscape as decoration and not a community of living organisms. If colored mulch encourages these kinds of homeowners to use organic mulch rather than synthetics or just leaving the soil bare, I’m all for it.

  15. Linda’s last comment inspired me to ask about a California gardening practice that has puzzled me for years: Why are gardens in California not mulched? Isn’t water conservation an issue there? Gardens, public and private,are typically bare soil. What’s up?

  16. Anyone from California have any insight into Nancy’s question?

    Gardeners in the U.K. rarely use mulch; ample rainfall is the probable cause.

  17. While I agree with Brian that if someone is commenting on your mulch than the focus is in the wrong place, I have to also note that the correct COLOR of mulch can either detract or enhance a landscape. I’ve never used die or colorants on mulch. We don’t have to. Here in Oregon we have plentiful and very affordable mulch varieties naturally. But by far, the preference is the darker varieties simply because it keeps the focus on the REST of the landscape. The darker mulches don’t stand out like the brighter ones do (e.g. red fir). They look elegant and toned down, not bright and flashy.
    So it keeps the focus on the landscape plants, trees and other features and off the mulch.

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