Wednesday, February 12, 2014

Becoming a Mulchologist!

Maybe just 2 more bags?
If ever such a professional title as a mulchologist existed, then last year I came pretty close to earning that accolade.  I hadn't given too much thought to the stuff until I was faced with some peculiar questions about are wood based mulches.  In fact, the more I dug into the world of shredded or chipped mulch the more I realized that it might be more foe than friend.

My training began early in 2013 as many landscapers and homeowners were breaking out of snow-mode and venturing back into the garden.  There's nothing better than cleaning up the remnants of last years fallen leaves or cutting back the odd ornamental grass to get us into the gardening mood again.  What better time to lay down that fresh carpet of mulch before all those perennials break through the ground.  Although not my favorite of mulch coverings, color dyed mulch has become very popular.  Black, brown or martian red, we sell enough scoops to probably pave the Washington DC Beltway (slight exaggeration).

The Lava flow
However, little did I know, you have to make sure that you have at least one dry day after applying the stuff or you run the risk of rain washing off the color.  So great is the demand for this colorful carpet, it is processed without time to properly cure.  Nothing is worse than waking up the following day after spreading it to discover your lava field of red mulch looks more like fresh milled chips spat out from an arborist's tree shredder.

For suppliers of mulch, one thing they have to watch out for is souring.  The large piles of wood mulch stored for long periods over the winter, or bagged mulch that remains too wet can undergo anaerobic fermentation.  This process converts organic matter into sulfides, acetic acid, ethanol and methanol, basically it becomes wood alcohol.  If not properly processed, this 'Moonshine mulch' releases gases that are toxic to plants, bleaching or scorching the foliage of surrounding plants and even running off into your lawn.  For some plants this can be detrimental, but woody plants will regrow any lost foliage once the hangover has pasted.  A quick sniff of the mulch, checking for an alcohol-like, vinegar or rotten eggs odor should alert to a potential problem before you spread it out.

We all know the virtues of mulching to control weeds and reduce moisture loss but it can be over done.  Excessive mulch will suffocate the soil and provide cover of rodents like my personal nemesis, the veracious vole, who likes nothing better than to chew off the roots of my plants undetected.  Long have we been told to not mound up mulch around trees, creating a volcano but it is still seen around our neighborhoods.

Lesser known but equally as damaging, is constantly re-applying mulch in annual layers.  Many of us don't realize the need to break up and aerate the crust that mulch can form throughout the year.  When shredded wood mulch is applied to thick and allowed to dry out, it becomes a breeding ground for certain kinds of water-repelling fungus.  This Fungus produces a mycelium mat, similar to roots of a plant, that becomes so dense it repels water.  The technical term is 'Hydrophobic', but this effect prevents moisture penetrating down to the soil, starving the roots of water.

The opposite of a Mulch Volcano - The 3ft deep, compact Crater

Now that's just not right!
Many microorganism live in and around mulch.  Some are beneficial to our gardens like mycorrhizal fungi. Others slowly break down and mineralize the mulch material, releasing nutrients that benefit the surrounding plants. However, some microorganisms can become a nuisance and become detrimental in our gardens. Who hasn't suffered from Tar spots on your siding or covering your car, fired from artillery fungus. And, what about those phallic toadstools from stink horns, aptly named for the stench they give off too. Nothing beats the slime molds. Commonly referred to as Dog Vomit Fungus as it looks just like its named! Wood based mulch is an ideal media for fungus establishment and if measures aren't taken to remove these annoying organisms, then the chances are great that they will re-inoculate fresh mulch after its applied.

These problems are just a glimpse into a bigger a debate about wood mulches dirty little secret.  I have been scarred by Artillery fungus's Tar Spot bombs and lost many plants from tunneling voles.  Gone is the desire to spread yet another 10+ yards of shredded wood mulch each and every year.  I confess, I'm cheap, but is there a better alternative?  Well according to Ohio State University Associate Professor of Agricultural Research and Development, Dr Dan Herms, the answer is compost!

In a study comparing ground or shredded wood mulch and composted yard waste it was found that the low Carbon to Nitrogen ratio of compost produced better plant growth and increased productivity.  The finding are too long to cover in this post, but isn't compost what we used to do before it became popular to buy shredded mulch?  It was only since the 70's that sawmills began removing the bark from logs in an effort to extend a saw blades lifespan.  Within a few years of that, nurserymen and landscapers were buying up all the waste from mills as an easy way to dress up our gardens.  Are we now beginning to discover some of the negative effects from this product.

So true Mr 'Most interesting man in the the World'
While I'd agree mulch is more aesthetically pleasing to look at, like icing on the cake, I would welcome something that improves the well being of my garden.  Gone for me are the days of bagging up grass clippings and fallen leaves for the trash truck.  For the past year I have been spreading my garden waste directly onto the beds and allowing those microbes to go to town on it.  Although the conventional wisdom tells me to process this material first, I've seen no negative effects on my plants.

One unexpected benefit I've recently seen is that neighborhood cats have been able to easily hunt down the voles.  It seems that these supreme hunters can seek out and attack subterranean voles better in compost than compacted mulch.  This is enough reason for me to continue using compost to mulch with but I suspect I will need to find more material to feed my gardens needs.  I'll have to keep an eye open for more curb side garden waste to use and recycle.  Someones trash will become my treasure!

Read more here, but don't forget to come back!


  1. I use compost--yes it doesn't last as long, but in all other respects it's been better.

    Is it just me, or is that stuff dyed red appalling?

    1. I agree about the red dyed mulch, its just so glaring on the eye. I've also hear of over colors being used but so far it hasn't made it into the market place.

  2. Excellent, well researched post. Dyed red mulch is hideous. It makes a garden/yard look like it was landscaped by Martians. I use a a weird, three pronged tool with a long handle to break up my thin mulch layer so moisture can penetrate it. When you break compacted, crusted mulch, it actually crackles. Potting soil can become hydrophobic in much the same way as mulch. Love the graphics. :o)

    1. So much for shredded mulch helping to retain moisture if it only repels it later. I've heard mixing a few drops of dish detergent in a watering can will combat the potting soil dryness. It basically acts as a surfactant, but maybe it will work on mulch??

  3. Lots of helpful information here. We do use wood mulch in some spots, but not the dyed kind. I like the smell of cedar mulch. Thanks for the reminder to break it up in the spring.

    1. Cedar mulch is really nice and used a lot by people concerned about bugs. I've considered using a smaller pine bark chip in the front of the house for appearance and going leaf/grass clipping in the back. The chips don't pack down and so shouldn't be a problem.

  4. Compost is the way to go! I have come across two publications recently from the US that are of interest, one is a collection of 25 articles from the magazine 'Fine Gardening' under the title of HEALTHY SOIL and the other is 'Our friend the eathworm' by Dr George Sheffield Oliver first published in 1941. The description of his Grandfathers farm in northern Ohio is worth the book on its own.

    1. One of last years gardening trends that some marketing company came out with was about consumers buying products that improve the health of the soil. So far I haven't seen that prediction come true but it is full circle back to what we used to do.
      I believe, but I could be wrong, the earthworm here in America was introduced from Europe as its own were believed to of died out during the last ice age. I've heard a customer talk about buying night-crawlers from fish bait stores and letting them go around his garden, just to get the soil tilled. Not very often do you hear of an introduced species that's of benefit.

  5. This is a really interesting post. I've done quite a bit of research on mulch myself - everything from pine straw and shredded wood to bark mulches, compost and more exotic mulches like pecan shells or cocoa hulls.

    It's a vast and bewildering mulch universe out there, I tell you!

    Ultimately, I've gone with pine bark nuggets here, for a couple of reasons:

    1. They're lighter and easier to spread than many other mulches

    2. They are durable. Unless washed or blown away, they'll last for years, so you don't need to reapply annually.

    Compost does make a good mulch, I think, but it won't suppress weeds at all and if you're in an area with high winds and/or heavy rain, a lot of it tends to wash or blow away, I think.

    So what's the real, ultimate, long-term answer? I think it's more plants!

    Of course groundcover plants have their own challenges (many of the most popular ones are awfully aggressive or even invasive), but I've been trialing a variety of groundcovers and have a few promising candidates that could replace much, if not all, mulch in my yard. Since the plants I'm talking about are perennials or subshrubs, ideally they'll come back every year, eliminating the cost (financial and environmental) and time associated with the Annual Mulch Spreading.

    What are some of the most promising groundcover mulch-substitutes thus far? For sun - Lamb's Ear (Helene von Stein variety) is probably the top candidate right now. For partial shade - various cranesbill geraniums and possibly Creeping Raspberry (Rubus calycinoides). For heavier shade, I'm thinking epimediums and ferns.

    Of course, these are only the options that work for me in my particular rather harsh setting (zone 6/7, lots of heavy mostly unamended clay soil, windy hilltop site, drought-prone summers). For those in cooler or more tropical zones, different groundcovers would probably rise to the top of the heap -- and there are new ones I plan to trial in 2014 and beyond -- but I still think that most landscapes could benefit from replacing most of their mulch with groundcovers of one form or another.

    1. So many options and so many problems. At the end of the day you need to go with what you like the most and adapt your practice's to meet the need of the material. I'll still use pine chips in high profile areas for the aesthetic's but will use compost in the back 40's so that I can recycle as much as possible. Maybe I'm becoming more aware of the carbon footprint but what growing in my garden should go into my garden. Thanks for taking the time to comment.

  6. I just read part of this article and people must know about the dangrs of colored mulch. I had a landscaper[Randys landscaping,Somers WI] buy the lot next to me and what happened is he raised his lot 12 inches and pitched all at me and he has two mountains of colored mulch within 50 feet of my well of which one is red colored and the closest. What is happening here is he constant flooding me I have 10 feet of collapsed foundation of my home and a well that has 17 different heavy metals in it not to mention a wrecked front yard. This guy was warned by me before he altered his lot and was told I have a well there, he did it anyway. This has been going on for 7 years and cannot use my water anymore, I've been living here for 22 years and it was only then when this landscaper moved in that the problems began. I've been getting my water from our farm for the past year from a 300 foot well. The only way we found out my well was polluted was two things happened first I was feeling ill for around the past couple years and couldnt pin point it and it was opnly when in july of 2013 I quit drinking the water and my symptoms of arsenic poisoning and fibro myalgia symptoms went away. second was a test done at the state of Wisconsin hygene lab in Madison WI did a terst on the color in my drinking water and it came back with 17 different heavy metals in it and was told not to drink or use the water it is unsafe. this guy has been letting his runoff from his lot go onto my well for 7 years and the Town of Somers Wi, Kenosha county officals. Peter Barca, Samantha Kerkman, Jim Kreuser, The D.N.R. a kenosha county envirnmental manager and ETC dont do anything, what does it take, somebody to get deathly sick or get cancer and die from this crap befors they do anything because that is my fear now is getting cancer from this runoff that has this colored mulch junk so plesae tell people to be very aware of this toxic junk.

  7. hello Rob... I am Denys... having a look at your blog at St Maarten's airport !

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