Do You Know Where Your Mulch Comes From?

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Moriuchi compost 5-25-2014 5-13-29 PMA pile of freshly ground mulch, but what’s in it?

My friend and longtime customer Caroline Moriuchi invited me for a guided tour of her family’s mulch production operation, M&M Mulch in Moorestown, NJ.  I jumped at the chance because I always wondered how mulch was made.  What I learned from my trip plus subsequent research is that if you don’t know what your mulch is made from, you should.


Moriuchi compost 5-25-2014 5-07-43 PMAs you can see in this photo, M&M Mulch accepts only wood chips and brush for grinding into their high quality mulch.

M&M Mulch, which is run by Caroline’s son Seiji with the help of his father and brother, has a company policy of using only wood chips from tree services and brush from landscapers for grinding into mulch.  They will not use wooden pallets, scrap lumber, or parts of demolished buildings to produce mulch, although this is common practice in their business.  For this reason, they do not produce red-dyed mulch because it can only be made from processed lumber like pallets.  I am going to show you the Moriuchi’s mulching operation, but first I want to outline some of the dangers from pallets.


Moriuchi compost 5-25-2014 5-36-19 PMMulch being ground at M&M Mulch

You should do your own research, but, after reading many articles, I would never use commercially produced mulch without knowing what it was made of.  The best article on the subject is in Natural Life Magazine, to read it click here

Basically, a lot of mulch is made from recycled shipping pallets.  If you drive down Interstate 95, you can see the huge pile of pallets waiting to be ground into mulch near Wilmington, DE.  A high percentage of pallets are contaminated with bacteria, including e coli and listeria, from the food transported on them and from improper storage.  They are often made from “engineered wood” which is treated with formaldehyde. 

The pallets themselves are often treated with dangerous chemicals, although this is being phased out.  If they come in from abroad, they are fumigated with toxic fungicides and pesticides, and toxic substances often spill on pallets during transportation.  Wood scraps and demolished buildings pose similar dangers from toxic applications like lead paint and pressure treated wood. 

Now we get to the fun part, how mulch is made:


Moriuchi compost 5-25-2014 5-03-23 PMThe mulch production process starts with this very big machine, the grinder.


Moriuchi compost 5-25-2014 5-04-43 PMThe grinder is moved around the production yard using this remote control.


Moriuchi compost 5-25-2014 5-35-26 PM  A front end loader is a crucial piece of equipment.


Moriuchi compost 5-25-2014 5-35-34 PM The loader scoops up the wood chips and brush from the giant piles waiting to be ground.


Moriuchi compost 5-25-2014 5-35-54 PMThe raw material is deposited into a hopper on the grinder.


Moriuchi compost 5-25-2014 5-06-46 PMConveyor belts inside the grinder feed the grinding teeth.


Moriuchi compost 5-25-2014 5-37-13 PMThe grinder produces a giant pile of mulch, but the process isn’t over because most consumers demand that their mulch be dyed.  I am not sure how this process started or why dark black mulch is considered more attractive than natural brown.  I personally think black-dyed mulch is hideous.


Moriuchi compost 5-25-2014 5-16-29 PMThe dyeing machine


Moriuchi compost 5-25-2014 5-24-42 PMThese paddles mix the ground wood with carbon black to make it black or iron oxide to make it brown.  M&M does not produce red-dyed mulch because it can only be made from pallets.


Moriuchi compost 5-25-2014 5-22-27 PMBlack-dyed mulch emerges from the dyeing machine.


Moriuchi compost 5-25-2014 5-22-54 PMBlack-dyed mulch on the right, brown-dyed on the left.


Moriuchi compost 5-25-2014 5-23-41 PMBrown-dyed mulch on the right, un-dyed mulch in front and on the left.  I think gardeners should question why they need dyed mulch.


Thanks so much to the Moriuchis, especially Seiji who answered all my questions, for the fascinating tour.  If you live near Moorestown, New Jersey, you are very lucky to have a safe source of mulch nearby produced by the fourth generation family farmers at M&M Mulch, 400 Hartford Rd, 856-234-2394.  They deliver free to the Moorestown area and for a fee to other parts of New Jersey.  Who knows maybe they can be enticed to cross the river to Pennsylvania!


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46 Responses to “Do You Know Where Your Mulch Comes From?”

  1. The tree nursery farm where I was working for years makes their own mulch, just as you showed it. They use the trees and trimmings on the farm. They only make the natural mulch, not the dyed. Most clients prefer the black mulch and are willing to pay $40 per yard delivered. Brown is $20-25 per yd. Black mulch was fairly recent here, maybe only in the last eight years or so. Once people saw it in the big box stores, it became the mulch of preference in our area.

    • Donna, It seems from my research that dyed mulch is a recent phenomena all over the country in the time frame you mentioned. Homeowners here are also willing to pay more for black mulch. Black is not a color found in nature and stands out like a sore thumb in a garden ruining the whole display. As you know from your design experience, the point of mulch is to unobtrusively keep down weeds not to be the focal point of the yard. Carolyn

      • Hmmm. I’m not sure about not found in nature. Last year we got a load of compost, which I used as mulch in some places, and it was *almost* as dark as dyed black mulch. Not so great at weed suppression though, but good for the soil, and makes pulling them a lot easier.

        We had the misfortune to lose a 150 year old pine from our front yard this year, but the good side is I currently know *exactly* where my mulch comes from. I watched it come off the tree and into the chipper 😉

        It does seem there would still be a worry that the trimmings from landscapers would contain residual pesticides, or herbicides, or whatever the landowner was treating their shrubs with before they were trimmed. I don’t know if the timber industry treats trees…seems like it might not be cost effective at that scale. Trying to avoid chemicals is hard work. I remember a few years ago when there was all that compost contaminated with a herbicide killing veggies and evergreens. But unless you don’t outsource anything, what can you do?

        (Fwiw, I don’t like dyed mulch either. We usually use pine, because I selfishly prefer the smell while working with it. Or compost. Or chippings…)

      • Cee, Compost does not make good mulch because, as you say, it is great medium for weeds to germinate. It should be mixed into the soil. Yes, it is black, but you don’t see it naturally in the landscape because it is in the soil. My point is that you don’t see great swathes of black naturally in the landscape. I read a Rodale institute report along time ago that concluded that any residual herbicides etc on chips and leaves leached out during processing so there was no danger. However, it’s something to think about. Carolyn

  2. Nell Jean Says:

    I know where my mulch comes from. The crew cutting power lines across the road in winter were kind enough to haul what they cut here ‘way up in a corner next to the woods and just out of the field. When it ‘cooks’ for a season He-Who-Mows will bring it across the highway to my spot where it awaits doling out to beds.

    Sometimes in the fall I shred leaves; sometimes I just let them pile up somewhere and decompose. My favorite mulch of all is pine straw, much of which just falls off the trees into place in the beds or requires minimal raking. I hoard pine straw for year ’round use.

    Funny about paying extra for something un-natural, Donna.

    • Nell Jean, We don’t need to pay for mulch either because we have leaves to grind on site and can collect white pine needles from the roadside. However, I understand that most gardeners do not have these materials and need to bring something in. I would just urge them to make informed choices. Carolyn

  3. Donna Freeman Says:

    Thank you so much for this informative posting! I will be sharing with friends. Always enjoy your posts from Oregon.

  4. Yes, this is definitely an issue, Carolyn. Good post! I use Marsh Hay from a local farm for my potager garden. For the perennial beds, in the past, we’ve purchased bagged, shredded bark mulch, but I think the bulk mulch from a local, reputable mulcher is a better idea. We use undied brown shredded bark mulch.

    • Beth, I used to use salt hay on my paths. I really like it because it has a nice look and color and it doesn’t break down. On the down side, it is expensive and there are environmental issues with its harvesting. We now use white pine needles which we get from the side of the road for free. Carolyn

  5. I am lucky to have to mulch/compost facilities (MMC Bark and Jolly Gardener) within spitting distance of my garden. Good quality, all natural and certified organic products are relatively easy to find in Maine.

  6. Jodi Pollock Says:

    Carolyn, do you know a good source for mulch in the Philadelphia suburbs?

  7. I make my own mulch from prunings of shrubs and trees, I never have enough but I don’t buy any in; it isn’t common in Italy to use mulch at all, if they did I fear they would want bright dyed stuff!

  8. nwphillygardner Says:

    Another down side to the use of black dyed mulch is that it holds heat….like wearing black clothes in the summer. Early in the growing season that might accelerate plant growth, but mostly it stresses out the roots of some plant material around which the black mulch is placed. Unnatural is unnatural!

  9. nwphillygardner Says:

    I’d really love a cultural investigation of why the red mulch is seen as appealing to certain homeowners. As a local nursery has told me, there’s definitely a market segment who love their red mulch, but I’m not sure anyone’s investigated to learn why. That might be helpful in helping to dissuade those folks from demanding it, although your explanation about the exclusive use of pallet wood does surely begin the argument. Thanks for that info, Carolyn.
    (At least I understand that the black mulch looks like moist, rich soil from a distance.)

    • Eric, I thought that the red mulch is supposed to look like redwood and that’s why people like it. To me it just looks like something McDonald’s would use in one of their playgrounds. I just don’t get it. Yes, the black mulch looks like really good compost, but that is not something that you would see on the surface of the soil so to me it is very unnatural looking. black is just not a garden color whereas brown looks great. Carolyn

      • nwphillygardner Says:

        Maybe it starts with McDonalds & other commercial landscapes!?!
        I see a higher frequency of the red mulch in the gardens of post WWII red brick rowhouses here in Philadelphia. Can’t help wondering if there’s an idea of “Color Coordinating”……and once it’s seen in the neighborhood as a good choice, I think others follow suit.
        But I think it might be easier to sway the corporate decision makers than private home-owners who might be emulating those commerical landscpaes with a focus on “tidyness” over all else.

      • All very good points. We can start a campiagn “Red mulch isn’t Green”.

  10. Always wondered if the chemicals to dye mulch was safe…

  11. Interesting post Carolyn. Also very interesting to read the comments and find out what others are doing or thinking about mulch. I buy (when I run out of my own) what is called Forest Mulch which is only finely shredded bark. I need to look into its creation after reading this post.

  12. It must be many many years ago since I last bought mulch. Now my garden is covered with plants and I only spread compost under the plants. Dyed mulch seems strange to me.

  13. We are lucky here to have so many Loblolly Pines that drop needles constantly, and I am particularly lucky because 3-4 times a year my neighbors put their pine straw in clear plastic trash bags and leave them on the street for the trash man to pick up, but usually I get them first. As hideous and as tacky as red and black mulch are, I prefer people to use that instead of cypress mulch which is being questionably harvested from the wetlands of Louisiana.

    • Les, I have also read that salt hay is harvested in an environmentally irresponsible way. There is nothing wrong with mulch, although I think that gardeners should buy the undyed form, as long as it is made from safe materials. From a design standpoint, I believe that the aim should be to fill in with plants so that mulch becomes unnecessary in the long run. Plants are less expensive overtime too especially if you hire someone to spread your mulch. Unfortunately the “mulched look” seems to have become an end in itself. Carolyn

  14. Thanks for yet another interesting post from you Carolyn. I have to buy my mulch, and I use a lot of it, but over the almost 13 years I have been here it has greatly benefitted the soil and made what was a soil on the slightly acid side a heaven for all the acid loving plants I have. I use a mulch made of ‘100% coniferous tree bark from mixed species’, and over here, dyed mulch is something used mainly for things like show gardens and perhaps on playgrounds, you can get it in pink, purple, blue and green etc. Never heard of black mulch.
    The mulch I use is the same as I have used since I moved in, it has a mix of different types of bark, and some pieces of wood mixed in, giving it a nice, speckled, very natural look once spread. Definitely not a ‘dyed’ look, and it smells lovely for a good while afterwards, like a lumberyard 🙂

  15. Boy would I love a safe source but even our local towns use all kinds of scraps besides trees so I buy pine bark mulch un dyed and hope it is from trees only.

  16. This is food for thought! I never questioned where the mulch came from! Especially the giant cheap bags from the big box stores! In our new community, most homeowners use pine needles for mulch which is a different look for me, but in tune with coastal Georgia, and definitely a renewable resource!

    • Jayne, You are so lucky to have those pine needles. Studies show that they do not increase acidity as one would imagine. Carolyn

    • My neighbor is a landscaping company that produces mulch and he has a big pile of pallet wood and scrap wood that he makes the colored mulch out of. He bags mulch that he sells to Home Depot or Lowes. I would not be putting that on my yard! His runoff has killed off the fish in our pond and caused algae bloom.

  17. Very interesting and informative post. Thank you. We are very lucky here on the west coast–the dyed mulch style has not really taken off here. It looks so extremely unnatural.

    One thing we run into here is mulch mixed with plastic garbage, asphalt, and broken glass–who wants that in their soil? Quality is just as important in the garden as in everything else.

  18. An expanding concern of home owners is the bulk mulch
    delivered to your home via dumptruck… it sometimes comes with termites. The bagged much is much better because it is
    manufactured in a facility and not sitting in a huge mulch yard where it can attract termites. I try to use cedar mulch next to the house.

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