Why Use Mulch?
Mulch has so many benefits in an organic vegetable garden. I wouldn’t even know how to garden without it. We are huge fans of lasagna gardening (which includes wood chip gardening), but even before we switched to no-dig gardening, we were big fans of using natural materials as mulch.
Why do we love mulch so much in our organic garden?
Mulching Reduces the Need to Weed
Well, first of all, because we don’t enjoy weeding a garden. Mulch does a fantastic job of preventing weeds from sprouting, and reduces the need to spend a lot of time weeding.
Mulch Conserves Water
Tender seedlings and newly sown seeds need a lot of water. After they are established, though, we don’t do a lot of watering unless we are getting particularly dry weather.
That’s because mulching prevents the soil from drying out and conserves water.
Mulch Builds Soil
Most importantly, organic mulch encourages soil organisms like earthworms, and feeds the soil as it decomposes. If you want to grow healthy, nutrient-dense produce, building soil is the way to go.
Some good mulching materials include chopped leaves, hay, grass clippings, wood chips, and newspaper. I sometimes even use rhubarb leaves.
Wood chip mulch is just one option out of many.
What is Wood Chip Mulch?
As the name implies, this type of mulch is made from chips of wood. But not all wood chip mulch is created equally.
Many landscaping companies sell mulch – you’ve seen the colored piles at their places of business. This mulch is generally made of bark, or shredded discards of the lumber industry, and is often lacking the nutrients your vegetable garden needs.
In addition, if the mulch is colored it may contain questionable chemicals that have no place in an organic garden.
Arborist wood chips are valuable in an organic garden–particularly ramial wood chips. Ramial chips come from small branches and leaves and are wonderful for building healthy garden soil. The leaves provide nitrogen to help break down the carbon in the branches.
Where to Get Arborist Wood Chip Mulch for Garden
If you are searching for soil building, ramial woods chips for your organic garden, I highly recommend that you begin by calling arborists or landscapers in your area.
We personally have made a wonderful friend by doing just that. We first met our arborist when a tree fell during a storm, crushing my car, and blocking the front entrance to our home. Alan quickly arrived on a Sunday and removed the tree.
We then hired the same arborist to remove a dying ash tree and asked him for the chips to mulch just the paths in our garden.
It was perhaps a year later that we watched the documentary Back to Eden, which dramatically changed our view of gardening. After watching the film, I began to observe that the wood chips that had been placed on our garden paths were decomposing and turning into amazing, black soil.
We were hooked and began to use wood chip mulch in our vegetable garden in earnest. This was not without challenges.
As I say in my post on using wood chips as mulch in a vegetable garden, of all the materials we have used as mulch in our garden, wood chips are the least forgiving. That is not to say that they aren’t worth it, though.
What Concerns Are There in Using Wood Chips for Mulch?
When using arborist wood chips in a vegetable garden, people have a lots of questions. What if the tree was diseased, or infected with insects? How deep should I mulch? Are there certain kinds of trees to use, or wood chips to avoid?
I’ll do my best to address those concerns here.
Types of Wood to Avoid For MulchÂ
There is the concern that some mulches leach allelochemicals into the soil which may kill nearby vegetation. It is accurate that these chemicals can prevent seed germination or even kill young plants.
Black walnut, tree of heaven, magnolia, and eucalyptus all exude allelochemicals. But that does not mean that those chemicals will kill all nearby plants; they each affect only certain species.
Maple, too, is known to have allelopathic tendencies and yet is quite safe to use as a vegetable garden mulch.
Black walnut exudes juglone would can be quite toxic to a number of vegetable plants, such as eggplant, tomatoes and asparagus. But there are vegetables like snap beans, beets, corn, onions, garlic, carrots, cauliflower, and squash which are not sensitive to juglone.
So, to be on the safe side, I would recommend never using black walnut as a mulch in your garden, and would be careful about tree of heaven, magnolia, and eucalyptus. A small amount mixed in with other types of chips should not be problematic.
Is it Okay to Use Wood Chips from Conifer Trees?
Wood chips from conifer species such as pine, spruce, fir, and hemlock are quite acidic. As the wood chips are decomposing, the pH of the chips themselves may be acidic. But this won’t affect the soil below the mulch, and once the wood chips decompose, the soil it produces will not be acidic.
The following information concerning the pH of different tree species is quite interesting. You will find that the pH of oak is just as acidic as those of several conifer species:
- Elm pH 6.0 – 7.2
- Oak pH 3.3 – 3.9
- Douglas fir pH 3.75
- Scots pine pH 4.3 – 4.6
- Source – The Woodchip Handbook by Ben Raskin
Still, many garden experts recommend that not more than 20% of your wood chip mixture be from coniferous species.
If you are still concerned, use only wood chips from deciduous trees on your vegetable garden, and save those from conifers for acid-loving plants like blueberries.
What About Diseased Trees?
Wood mulch should never be dug into the soil but used only on top. Studies show that diseased mulch cannot transmit pathogens to the roots of healthy trees.
Not as much is known about it ability to infect vegetables, although it is thought unlikely. Keeping the mulch on the surface of your soil will keep it away from the roots of your plants.
What About Trees With Insect Infestations?
Many insects are decomposers; their job is to feed on rotting organic matter breaking it down so that healthy soil is built in the process. So, yes, you will see insects in your mulch, especially at the point where the mulch meets the soil.
For this reason, it is best not to allow mulch to touch your home or other structures so that insects are not able to enter and do damage.
But what about using mulch from a tree such as ash, for example, that is infested with the emerald ash borer? A friend asked me this question recently since they were cutting several ash trees on their property and wanted to use the chips as mulch.
There really is not a lot of information about this to be found but I contacted our arborist and our local extension agent. Both informed me that it is highly unlikely that using such mulch would harm vegetables. That is because insects like the emerald ash borer are species specific. They only feed on very specific plants – the ash tree in this instance.
So, it is would be wise to know what you are getting, but in general mulch from a tree that has been killed by an insect should pose no problem in your vegetable garden.
How Deep Should I Mulch With Wood Chips
This is an important question and is essential to your success in using wood chips as a mulch in your vegetable garden.
As I mentioned, of all the types of mulch we have used, we have found wood chips to be the most unforgiving. It is essential that wood chips be used properly.
I have found that 2 – 3″ is just right for wood chip mulch. Most problems from using wood chips result from mulching too deeply. Be sure to read my post on using wood chips as mulch in a vegetable garden for more information.
To learn how to build a garden that builds healthy soil, be sure to check out my eBook The Art of Gardening: Building Your Soil.Â
You really can become a better gardener, and you really can grow healthy, nourishing produce. It’s all about the soil! Click here to learn more.
More Organic Gardening Posts You’ll Love
10 Common Mistakes When Using Wood Chips in Your Vegetable Garden
What are Ramial Wood Chips and How to Use Them
Lasagna Gardening – an Easy and Productive Way to Garden
Using Wood Chip Mulch in a Vegetable Garden
Plastic Mulch in the Garden: Friend or Foe?
Are You Killing Your Trees With Mulch?
Hay vs Straw in the Garden: Which is Better?
6 Simple Steps to Planning a Vegetable Garden Each Year
Source, Source, Source, Source, Source
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Patricia Collins says
Very slow
steve says
Mulching plays an important role in conserving water. There are different materials that can be used as Mulching materials but it’s good to know that not all wood chips are ideal for mulching.
This post will go along way in helping organic gardeners who are very green on matters wood chips and their use on vegetable gardens.
Susan Vinskofski says
Thanks for stopping by, Steve!
Connie Noguchi says
I have a ton of wood chips from our huge lychee tree which had to be cut down…. I am hoping it is a good wood. My dog likes to eat it, so it must be non-toxic?? Thanks for this article, though. Very informative.
Susan Vinskofski says
Just remember to only use an inch or two if you’re using them as mulch for your vegetable garden.
C says
Wood does make amazing compost, takes 3 years to make good compost according to Bando organics. At my new garden place (community garden), they just truck it in, and we are not allowed to compost because it can attract critters. Neither are we allowed to bring anything in from anywhere (jumping worm). I was a little surprised at first to see how fast wood chips will break down and turn into dirt. I used my compost area as a dumping grounds for invasive, then clean it out periodically. Otherwise I would just grind anything I could find under, hay, straw, leaves, wood, and let mother nature do it’s thing, worms were prolific, robins would be friendly with freshly turned dirt, even the chickens would come over to see if I might find a grub to toss them. Now, at my new plot I have yet to see a worm, even though it’s supposedly organic, something is different, and miss my larger weedier plot, it just seemed more bio-diverse in some way. It seemed that tilling with a mantis gave me more control over not having to feel like I’m over-tilling. And, it seemed like just hitting the top really helped keep weeds down without disturbing the soil so deeply. Weeding, although work, was so easy when the ground is wet.
Steve D says
I work for a horse charity and we buy very expensive, dust, chemical and bark free woodchip for post operation/ recovery turn out areas. These are fully drained arenas so the woodchip stays in relatively good condition, however they are replaced roughly every 3 years. Would the material that we remove be good for mulching? It has normally just started to decompose slightly at the very bottom of the arena.
Susan Vinskofski says
Yes, absolutely! Don’t let it go to waste. 🙂
Roxanne Ochs says
I have a few Canadian Red Cherry trees that I am going to remove. I want to put them into the chipper and use them as mulch. Are they safe for this purpose?
Sarah Adkison says
We have chipped crepe myrtle branches. Are they safe as mulch?
Can they be added to our compost pile?
Thank you
Susan Vinskofski says
Hi Sarah, crepe myrtle should be just fine for mulch and your compost; I see nothing about them that says that they are allopathic.
Paula B. says
My silver maple trunk was covered with thick tree ivy when it was taken down. Is it safe to use the chipped wood as mulch in flower beds?
Susan Vinskofski says
Hi Paula, I would be concerned about the tree ivy taking root wherever you put down the mulch. If you can age the mulch for a while until you are sure all of the ivy is dead, then it should be just fine.
Nadalca hynes says
My husband just cut up our winter wood lots of wood chips and saw dust so can we use this in our Rose garden and around our trees and flowers thank you
Susan Vinskofski says
Wonderful!!!
Seth says
I had green giant arborvitae delivered chipped from a tree company. Not what I choose to have but I wanted some free material to start a mulch layer for a good forest. Will this work or will it break down properly? It’s looking like it will be difficult to walk on and I’m wondering if I need to spread it thin and go over it with better wood chip mulch because I’d hate to waste it seeing how I have two huge piles in my yard to use somewhere
Susan Vinskofski says
Hi Seth, I think that you will find this article by Linda Chalker-Scott interesting and informative: https://s3.wp.wsu.edu/uploads/sites/403/2015/03/aleopathic-wood-chips.pdf. Especially since you plan to use them for a forest, I think they will do just fine.
Bill Redford says
Would stump grindings from a magnolia tree be ok for composting?
Susan Vinskofski says
Magnolias are allelopathic which means that they produce chemicals that inhibit the germination of seeds and limit the growth of other competing species that grow underneath it. I would compost the stump grinding separate from anything else and be sure that they are completely decomposed before using in my garden. I would also then test by planting some seeds in the compost to see if they germinate.
Karen says
I had a 5 ft oak stump ground and there is lots of wood chips/mulch, of course. Is it safe for my lab to walk on it and sniff around? Thanks so much!
Susan Vinskofski says
Untreated wood chips aren’t likely to cause harm even if your dog ingests it.
patrick hart says
We have 50+ juniper trees and a few Chinese Elm. Can chips from these trees be used as mulch? I heard that the soil around the Juniper could be used for planting after 3 yrs if you move the soil to a location away from the Juniper. The soil looks very rich.
Patrick
Susan Vinskofski says
Juniper may have some allelopathic properties, but would probably be ok if 1. not more than 20% of your wood chip mixture be from this coniferous species, 2. you don’t spread it too thickly (under 2″) and 3. you only use it where you will be planting seedlings, but not direct sowing seed. I’m not familiar with Chinese Elm; if it has the same properties as Elm, it should be ok.
Chelsa says
We have a bunch of holly bushes (trees!) that I was planning to chip, but I’m unsure if it would be okay to mulch with them in the vegetable garden because I know those tend to be toxic for animals to eat. Would holly wood chips be okay?
We also have loads of blackberry bushes that we could potentially chip, but would that encourage blackberry bushes to grow in my garden?
Thank you so much!
Susan Vinskofski says
Hi Chelsa, my understanding is that there is no reported evidence of allelopathy in Holly, so it should not be detrimental to the growth of other plants.
As far as the blackberries, I’m not sure; they do root from stem tips. But I would think that composting the chips for a time would solve that problem.
Thanks for stopping by!
Tom Howard says
Is a small amount of any of these;(Black walnut, tree of heaven, magnolia, and eucalyptus) mixed in with other types of chips, not be problematic?
Susan Vinskofski says
Hi Tom, that’s a hard question to answer. I would think it would be ok, but I haven’t tried using any of these wood chips myself – either alone or with other chips – to say whether it would be a problem or not. I would start with a small area and see how things go.
Susan says
Just discovered your website, Susan! So my question is about mold on wood chip mulch. We moved into our current home less than 2 yrs ago. Last summer was especially hot and dry here in south Texas. Been in ‘extreme’ drought for a good while. No matter how much we tried to water and save the beautiful ‘lawn’ the previous owners had cultivated to sell the house, most of the front yard (corner lot) with no shade just turned into desert.
We got an arborist load of live oak wood chips from our neighbors in the fall. We laid cardboard (from shipping boxes) directly on the brown, parched ground, and spread out the wood mulch on top. Nothing planted there. Maybe a pollinator garden later.
Now, miracle of miracles, we’ve been getting hard, heavy rain. Spring time. Tornado season. There are now all these weirdly shaped, flat patches on the mulch of something that looks like liquid pancake batter that spilled and dried. Some is brown. Some is whitish. Some is orange with slight texture like tweed fabric. Maybe some kind of mold or fungus?
Have you ever seen anything like this? Did we do something wrong?? Should we try to remove it all and somehow dispose of it? What would you do or suggest? Thanks so much!
Susan Vinskofski says
Hi Susan! You did nothing wrong. Molds and fungi are just part of the process of decomposition. You don’t see it much in dry climates but now that you are getting rain the decomposition is full speed ahead. As your mulch decomposes, nutrients are released that go back into the soil, which will actually benefit your plants. If you find it unsightly, you may remove it, but it is not necessary to do so.
Thomas E Welch says
We have pine trees which the previous owner had them planted and put visqueen then wood chips (they had the house built and were here for 30 yrs) then put grothinhibiture and more wood chip and finally the same again. So i have 2 layers about 8″ of fine roots, dirt and wood chips then about 2″ of fery fine tree roots. Our plan is to mix with our mulch (chips and chicken poop) and garden waste along with irrigation water. Moist but not soggy, I have a roto tiller type tool that i can use to mis about every three weeks. Does this sound adaquate?
Susan Vinskofski says
I’m really surprised that the trees survived this; quite honestly, I would contact an arborist for advice on the best way to go forward taking care of them.