A question about wood mulch

Hello everyone,

I am just starting to build a new set of garden beds.  I need a place where I can get a fence around the whole garden to keep out the deer and my present location just won’t suffice.  I am planning on fencing off a pretty good sized area, something like 40’ by 60’.  I plan on having several raised bed gardens in there and for those I will be using wood chips that I chip up myself.  But I just can’t chip up enough to fill in the beds plus all the walking areas so one thought I have is to buy in hardwood mulch from a local distributor.

The type of mulch I am thinking about is sold as being undyed.  At the distributor, it sits in a huge mound and is fairly evenly brown throughout.  And by brown, I mean a chocolate brown.  The wood is shredded up and is fairly light and fluffy.  I have used it in the past, a couple of times to fill in a flour garden that needed material owing to the fact that the bed had been built up multiple feet because of landscape masonry and I didn’t want to spend the money for actual fill.  When I did this, I could grow just fine as long as I kept the plants watered (they dried easily at first) until the mulch rotted down at which point it made a fine bedding for flowers.

What I am really asking is if this type of mulch is actually undyed and brown due to oxidation—in the summer, the huge piles at the distributor steam dramatically and sometimes have to be broken up to avoid fire, one actually did catch fire!  Or does even this mulch get dyed.

This of course leads me to the second part which is would this be acceptable to use as a ground cover for walkways.


Thanks in advance!!



Eric

Have you looked into ChipDrop?

I've gotten several loads.

Free, delivered right where you need it if accessible to a dump truck, lots of fresh leaves mixed with wood chips, small branches - an ideal ramial mix for composting. I've laid it on thick over cardboard for pathways, and after a year I've redone the pathways to root out the persistent grass stolons and roots. I found the year old chips to be loaded with earthworms, fungi and black soil underneath. So the pathways ended up with better soil than the beds!

You can also choose the option of random wood logs and pieces as well. Good for hugel building, biochar production, or burning for heat.

B Beeson,

Hi.  Yeah, I have looked into that option.  I put in a request several years ago.  I have yet to hear from them!  This is some pretty big lumbering territory so maybe that has something to do with it?  Really, I don't know.  That would be a great option, but it just has not worked for me which is why I not chip up my own chips for my beds and why I am looking into mulch for my pathways.

Thanks though.


Eric

Eric Hanson wrote:  This is some pretty big lumbering territory so maybe that has something to do with it?

I also haven't heard a peep from chip drop. We moved to Nova Scotia 3 years ago and it was only this past winter I learned that the lumber folks usually sell their chips and sawdust to the power companies who burn it for electricity. :-(

If it’s any color other than the color of cut wood, then it’s dyed. Wood chips on their own do not get steamy when left in a pile. Also there’s the smell. Dyed mulch has a strong smell, almost sour. Plain wood chips just smell like wood.

Nick,

Here is the dilemma,


The color is about the color of oxidized wood, and I have seen wood chips get extremely hot—my own piles have gotten that way.  In fact, it is the fact that this shredded wood was damp and being shredded was also aerated that the conditions seem just about right for microbial life to thrive and thermophiles to dominate.  The smell just smells like wood—absolutely no chem smell whatsoever.

Eric

Eric,

I wonder if you can obtain some and soak it in a bucket of water? I'd imagine if there is dye that it would run into the water and be suspended. This is just a semi-educated guess but might make you feel more comfortable before proceeding forward with getting a large quantity.

I've seen some shredded forestry mulch that was really rich looking because it was pretty much already composted. They wanted a price higher than free so I passed sadly.

Timothy, those are really good ideas!

The mulch you are describing sounds close to what I am seeing.




Eric

Hi Eric,
It seems like your original issue was filling raised beds? And the assumption was that you were going to fill it with woodchips of some kind?

If you just need to fill up some space, without wanting to fill it with something expensive, what about rocks or logs/branches? It might not be allowed on public land... but I know a lot of farmers who would give away rocks for free if you picked them up. And I know a lot of land owners that would not mind you picking up dead branches and logs from the ground and taking them away. In both cases, you would not need to worry about dye.

Keep in mind that mulch sold at a store is most often shredded bark... which is quite different to wood chips you might get from an arborist. But if it looks like the mulch is the best choice, I like Timothy's idea of soaking a small amount first to see.

If you are going to fill a raised bed, plants need soil, so just woodchips will suppress growth until it's completely broken down, which could take years.

The trouble I have with heavy clay soil is that even if there is rodent wire at the bottom of the raised bed, voles/gophers, digging rodents can still dig around under that wire and create air tunnels that roots go into.  I can't get under the raised beds to stop that, so I've stopped using them.  Digging rodents also are brilliant at using any stick or board as a solid roof over their entrance, and they just go to town under there.

You used the word "mulch," so I'm guessing wood chips are just for the top.  That has worked well for me.  The smaller the chips, the better.

If you are going to put branches or logs in the raised bed, be sure the wood at the bottom is rotten enough to break with your foot, and doesn't fill up more than 1/4 of the height of the bed.  If you put another layer of really rotten wood about 4 inches down from the top, make sure it's pithy and you can break it with your hands.  Then the plant roots can get into it and get the moisture.

Large, thick layers of wood chips on a path are good because roots also go under the paths and can benefit from the decaying wood.

Piles of wood chips definitely get hot!!  

Why not ask the distributor?

My feeling is that a big mound has not been dye as if the distributor was dying it it would be sold off quickly.  Though I don't know ...

Timothy Norton wrote:Eric,

I wonder if you can obtain some and soak it in a bucket of water? I'd imagine if there is dye that it would run into the water and be suspended.

You can get brown pigment out of pure wood mulch too, just normal oxidation products. When I potted trees in plain sawdust, any water that filtered out was a rather ugly brown. What started as bright sawdust also aged to reddish-brown and then dark brown.

Matt, Cristo,

Regarding the chips filling the garden beds, I think I might not have been clear.  A few years ago I began filling my beds with wood chips and then breaking them down with Wine Cap mushrooms.  The resulting compost is amazingly fertile, the best garden bed I have ever seen.

I plan on repeating this process in the new beds with the chips I produce.  However, the hardwood mulch/chips that I am thinking about importing from outside will strictly be used for walkways around the beds.

I hope that clarifies things.


Eric

Eric Hanson wrote:Matt, Cristo,

Regarding the chips filling the garden beds, I think I might not have been clear.  A few years ago I began filling my beds with wood chips and then breaking them down with Wine Cap mushrooms.  The resulting compost is amazingly fertile, the best garden bed I have ever seen.

I plan on repeating this process in the new beds with the chips I produce.  However, the hardwood mulch/chips that I am thinking about importing from outside will strictly be used for walkways around the beds.

I hope that clarifies things.
Eric

Now I follow you :)

In this case, if it was me... I would do my due diligence to find out if it was dyed. If no one knows... then I would pass, and see about planting a green mulch of clover or something in the paths. But I have the bad habit of waiting at miserable until perfect comes along. I do not suggest people follow my lead. Even dyed mulch in the paths is probably not that big of a deal.

I would try sprouting some seeds of various plants in soil mulched lightly with the chips, including legumes that are chemically sensitive, to see what is affected.

Matt, Ben, Everyone,

Regarding the paths, I have thought a lot about planting some type of cover crop so that the garden beds could get a little feed from the sides.  I may well entertain this idea at some point.  Right now, I have some well-established pasture grass along with herbaceous wildflowers that will absolutely dominate unless somehow suppressed.  My preferred approach would be the compostable weed barrier plus a layer of hardwood mulch/wood chips.  After those long-dominant grasses are gone, I would be totally fine with planting something like Austrian Winter Peas as an annual cover crop.

I just bush hogged out the approximate dimensions.  I will try to get some pictures up soon.



Eric

A worm avoidance test is another good way to suss out an "unknown" in a product like dyed mulch (or biochar, which is how I came across it). Fill a bin with good quality soil, add your mystery material to one half of the bin, and put some earthworms in there. After a week or two, carefully unload the two halves and do a worm census. If there is something problematic in the wood chips, the worms will be turned off by it and you'll see a difference in numbers between the two sides.

Hello Eric, no help for your immediate mulch requirements however, have you planted any trees that can be coppiced to provide a regular supply of mulch in the future?

Hazel and willow grows very quickly and are useful for weaving fences too.

Hi Megan,

The answer to your question is—sorta.

I haven’t actually planted any trees for coppice, so in that respect, the answer is “no.”

But I have a long, living fence line that easily gets overgrown.  From time to time I need to trim it back and I save those cuttings in a huge pile until I am ready to chip at which point I rent a 12”, 85HP diesel chipper.  I can’t possibly ever afford a chipper like this, but using one is SO much better than using a little 6” chipper.  Renting is affordable every couple of years.

Long winded answer to your question is that I have a system in place for doing exactly what you mentioned!  Great idea!!


Eric

Phil,

The more proposed tests get mentioned, the more I think this shredded hardwood is safe.

From memory of past times I have used this, as long as the wood was wet, worms thrived.  Specifically, I am thinking of a flower bed that I filled and then planted with creeping phlox.  It was really beautiful as over time the phlox spilled over the edges of the retaining wall and drooped down the side.  Phlox was also about the perfect plant as it was nitrogen fixing.

And the volume of the mulch plummeted over the first two years.  This was an annoyance at first as I had to keep bringing in more, but I didn’t mind so much as it indicated that there was decomposition taking place.  And again, as long as it was moist, worms seemed to love it.

If I don’t have enough wood chips on my own, a couple of loads of this mulch might be the right thing!


Eric