Friday, January 21, 2011

The Case Against Mulch Rings


It’s a common sight in the American landscape: trees skirted with a ring of mulch around their base that float in a sea of lawn.  Landscapers started the practice to prevent mowers and weed eaters from damaging tree trunks, and many arborists like the protection that mulch gives to the roots.   But listen up America:  these mulch rings have got to go.  The benefits of mulch rings have long been exaggerated, and they are just plain ugly.  Consider a few reasons for eliminating this practice.
In nature, plants happily share space with tree roots.  Why do we add the rings?
The first reason given for using mulch rings is for the convenience of lawn maintenance.  Having several feet of mulch around the base of the tree keeps mowers and weed eaters away from the trunk, preventing damage and soil compaction.  These are indeed valid benefits.  But I would first question how convenient these rings actually are.  I spent almost a decade doing professional landscape maintenance, and the rings eventually become more trouble to maintain and edge than it is to mow around the base of trees.  The truth is, it’s just not that hard to cut grass around trees without damaging them.
Forget convenience: mulch rings are downright ugly.  They make Swiss cheese out of an otherwise attractive and continuous lawn.  Why can’t the lawn grow right up to the trunk?  It’s beautiful.  Look at all the great gardens of Europe.  They never use mulch rings.  Mulch rings are another example of how we’ve sacrificed aesthetics for the convenience of our motorized tools. 
Lawn growing up to the base of trees creates elegant, park-like feeling
A client of my former firm had a beautiful lawn punctuated with large canopy trees.  We had removed nearly four acres of lawn on their property and replaced it with more sustainable gardens.  But they wanted to keep the front lawn.  Their landscapers had surrounded each large tree with a small mulch ring, making their lawn look fragmented and random.  We re-seeded lawn right up to the base of the trunks.  The result was staggering.  The space felt continuous and park-like. 
But isn’t mulch good for trees?  And doesn’t lawn compete with the trees for nutrients?  Mulch is indeed good for trees, and lawn does compete with trees for water and nutrients.  The problem is that the feeder roots of trees extend much beyond the mulch rings.  In fact, feeder roots can actually extend 20-50 feet beyond the dripline of the tree.  The tiny ring of mulch around the tree base covers only a fraction of the overall area of the roots of a canopy tree, negating much of the benefits of mulch.
What’s worse is that mulch rings encourage over-mulching at the base of trees, one of the worst things you can do for your tree.  The area where the trunk of the tree hits the ground is called the root flare. When you bury the root flare under mulch or dirt, it encourages the roots to grow upwards instead of outwards.  Roots that grow up are especially dangerous, as they often wrap around the trunk and girdle the tree.  If you have a trees buried under a volcano of mulch, it is gasping for air.  Dig it out and expose the flare.  
Native heuchera growing with oaks, Pierce's
Woods, Longwood Gardens
 Anytime you plant trees in lawns or planting beds, there is, of course, extra competition for water and nutrients.  Good basic garden maintenance—watering, thin applications of compost, feeding—will allow both to peacefully coexist.  Spraying compost tea over your lawns is a wonderful way to give both your lawn and the tree rich microbial stimulation without mulch.  Harvard's compost tea program is especially inspiring method for organically feeding both lawn and trees.

When it comes to trees in planting beds, I am a huge advocate of planting right up to the base of tree trunks.  Arborists tend to discourage this practice, but if you’ve ever walked through a forest, you’ll notice literally hundreds of plants happily sharing root space with trees.  Use plants (particularly native herbaceous species) that have evolved to grow on woodland floors.  Some of these plants actually have symbiotic relationships with tree roots.  Moreover, the aesthetic benefits of planting right up to the trunk of the tree cannot be overstated.  It’s incredibly beautiful, and with regular maintenance, does not have to pose a threat to trees.
Get rid of those mulch rings, and let lawn or plants grow right up to the base of trees.  Your lawn or garden will look a million times better for it. 
The beautiful effect of Trachystemom and Euphorbias growing right up to
the trunk of this holly at the garden of Ching-Fang Chen in McLean, Virginia.

32 comments:

  1. Great point. Your first photo reference looks like something from outer space or an abstract art installation.
    How about the other pet peeve in mulching: red mulch? This type of mulching is usually covering more than half of the bed with small shrubs spotted over it. Where to real landscapers get off doing installations like that?

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  2. Very interesting, valuable article. Agree with you totally. Thanks!

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  3. Yes! Thank you. I have always questioned this wisdom about mature trees. Naturally, my trees have grass at the base. My question is why landscapers need to use the trimmers that spin so hard and so quickly they would girdle a mature tree. You're trimming grass! You need that much force to trim grass?! Residential models don't have nearly that much force and bushwhack fairly well for everyday use. This whole post is just another reason why I do not like professional landscaping crews. They just aren't careful about their work and I refuse to change my garden to accomodate their sloppiness.

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  4. Great post with wonderful pictures to further illustrate your point. Have you seen those horrid plastic/rubber mesh rings that fit around the base of a tree? They are even worse in my book.

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  5. Thomas--I agree--except I just recommended mulching some (very small) oak saplings in a turf area that is used for occasional camping (but definitely not volcano mulch!). The mulch serves as a visual reminder to walking people and riding mowers that they are there. We may also put some little fences around them. When they get big enough the mulch will go.

    I also find mulch useful for smothering grass around trees preparatory to putting in native plants.

    Also, sometimes you have to mulch under Norway maples (grass won't grow there) in order to help build the soil while you are finding plants that will grow under them.

    Compost tea: good idea. I'm sending that NY Times link to the director of facilities at my college.

    Adrian

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  6. Thomas, I agree that the look of unmulched trees is wonderful!. Mulch rings too often lead to mulch volcanoes, a landscape feature that drives me nuts (they're a way for landscapers to sell more mulch, and unfortunately the trend is copied all over by landowners who see it and think it's the thing to do.

    But mulch rings of a reasonable height do serve a valuable purpose -- they keep the landscapers (and homeowners, too) and their damaging weed whackers away from the tree trunks. It doesn't take too much repeated trauma from string trimmers to damage bark, and then cambium, and even if a tree isn't girdled, trunk injury can shorten a tree's safe life.

    Landscape conditions make a difference, too in the decision of whether or not to use mulch rings. In a large public park, where compaction from heavy foot traffic can be a problem, very large mulch areas can protect the soil, add organic matter, and make oxygen more available to tree roots. In a residential setting where compaction from traffic may be less of an issue and where a knowledgeable homeowner can dictate how the lawn is mowed, how soil is fed and cultivated, and how/if string trimmers are used, then a mulch-ring free landscape is clearly more appealing.

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  7. I am convinced. In fact, I have been wondering how to rid my Betty Magnolia of its mulch ring and blend it into neighboring beds. I am going to try seeding some perennials because I fear I'll damage roots by digging in plants. Or is that an overabundance of caution?

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  8. I agree, including Deb's comments. Though the other extreme practice here in the SW and So Cal - no mulch at trees, lawn right up to trunks - may not be good, either.

    I think of a mulched area at bases of trees as beneficial, but only temporarily - 1 or 2 growing seasons. Just enough time for tree roots to establish better with less competition from grass roots, and the trunks to develop thicker bark, more resistant to weed-whackers. Planted trees don't have the same establishment of woodland trees, requiring a cultural leg-up, I think.

    But perhaps there is some research to prove otherwise?

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  9. Deb,

    I perhaps should have been more qualified in my statements about mulch. I received a very eloquent email today from the Vice President of the New York Botanical Garden explaining how much damage large mowers have done to their stately trees. He mentioned the benefits that mulching had done to some of their trees that were suffering in lawns. They have turned large areas of lawn into mulched beds, and their trees have prospered as a result.

    Perhaps the larger question is should trees be planted in lawn? I understand the need for mulch rings during the first few years of a trees life. But for me, tiny rings of mulch seem like token gestures for trees and they really wreck the continuous effect of a lawn. Plus, more times than not, they allows careless landscapers an opportunity to over-mulch.

    I object to the way American landscapes draw boundaries in the ground between different maintenance techniques. Mulch here, lawn here, planting here. I’m always enchanted by landscapes that have continuous and expansive ground-planes, be it perennial plantings, lawn, or mulch. Harvard Yard’s regular treatment of aeration, compost top-dressing, and compost tea strikes me as one way to enrich the ground for both trees and lawn alike—without the silly rings.

    It’s too bad that careless lawn maintenance necessitates mulch rings. Our landscapes are marred by the ridiculous logic of poor maintenance.

    Thomas

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  10. I couldn't agree with you more (we call them mulch volcanoes), but I would extend the plea to getting rid of shredded hardwood mulch everywhere. It is hideous not just in rings around trees, but even more so in great expanses in sparsely planted beds like parking lot islands or "foundation plantings" (why do we need those exactly?). It is not environmentally sound: real trees are logged to produce it, and it contains all kinds of potentially noxious molds and fungus. And it's expensive.

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  11. What do you think about peanut shell mulch around rosebushes? Roses have surface roots, and we have a mediterranean climate. Those roots need all the help they can get. If it is help?

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  12. Interesting post. As a British landscape designer / historian who studied and worked in the US, I found all those mulch volcanoes alarming and bizarre. They seemed to be exactly as you have described - an ugly, probably harmful reaction to obsessive mechanised maintenance. It's good to hear that my alma mater is now leading the way in more sensible, organic practices.

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  13. Interesting post and comments... there are valid points on both sides of the issue. Your mulch pics are definitely the extreme, and very unpleasant to look at. I actually prefer a very small circumference dug around the tree, and a couple of inches below the grass. It serves to channel water to the roots of the tree rather than the grass in our desert climate and protect the tree from the lawnmower... no trimmer needed and a very natural appearance. Whereas if I allowed the grass to grow up next to the tree, I would have to use a trimmer to keep it tidy and to discourage unwanted insects from taking up residence. The end result is a natural appearance with no damage to the trees.

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  14. Does mulch benefit new / younger trees trying to establish? What about mulching for 5 years, then bringing the grass back in? Or do you think there's no beneift to a new tree, and that grass can just come in right away after planting?

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  15. I have seen photographs of studies of mulch vs. lawn under boulevard trees and the mulched tree does grows significantly faster. These trees were mulched to the drip line not a small circle around the trunk. It is better for the tree than lawn but you've made some great points here. The aesthetics of our mulch volcanoes or mulch deserts are awful. I think the less disturbance to the tree root system is best. Smother the grass once, and plant with a herbaceous understory and let the fallen leaves build up organic matter.
    Heather

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  16. Great post and thoughtful responses. My favorite approach is trees growing through ground covers.

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  17. I find it funny that you want to trade mulch for turf. Get rid of both. Many accept the look of wall to wall carpet grasses as natural, but most have been coaxed and cultivated and brought from distant lands to create a very un-natural effect, requiring fuel hungry, carbon spewing equipment to maintain. Instead of seeding right up to the trees, expand those tiny rings to large conglomerate areas where you can mulch at an appropriate rate, feed all the roots, protect all the roots from competing grass and plant symbiotic plants beneath those trees to promote their vigor.

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  18. I think the rubber tree rings I used on 3 of my trees/shrubs actually harmed them. One died and the other two have been struggling to live since last summer. So today I took the rubber rings off and pitched them. Now I think my orange tree and knock out rose will flourish.

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  19. The addition of mulch under a young tree is intended to mimic the characteristics of a healthy forest floor, which is covered with a layer of decomposing leaves/biomass. Mulch is added until the tree has grown to a sufficient size that it is creating its own layer of biomass from its falling leaves and dead branches.

    Biomass under a tree accomplishes a variety of functions:

    - to retain moisture
    - reduce erosion
    - To inhibit the growth of weeds
    - to breakdown over time and improve the fertility of soil

    I agree that the mulch rings photographed in the image header of this article are somewhat absurd looking and far from functional, aside from their reported abiltiy to inhibit mechanized mowers from crashing into the trunk.

    Working with agroforestry and land restoration I cringe when I see bare earth beneath a tree. From a form-through-function standpoint, forget the costly, labor intensive lawn entirely and replace the whole thing with a thick layer of biomass. Decomposing organic matter is the essential source of all life on the planet.

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  20. If you see improper, volcano mulch rings, find out who the landscaper is and don't hire them! This is a sign of a company that doesn't care about their customer or their craft. A true landscaper will take the time to do it right and if a ring is required, they will do it right! This is a monkey see, monkey do phenomenon that needs to stop!!!!

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  21. Every single landscape job in our new subdivision included mulch rings around two oak saplings. Perfect Cuts is the landscaper.

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  22. The composition of the mulch also makes it weighty enough to withstand strong winds without blowing away. Black rubber mulch is relatively simple to use and involves no specialized equipment or machinery to install.

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  23. I made several mistakes within the 20+ year life of my live oak, including planting the tree directly from a pot, planting flowers at the base and the "mulch volcano." I've employed a tree service that recommended mulch (approx. 2/3 of the drip line). This tree business used arborjet, along with root feeding. They also severed the big girdled root. I'm convinced that mulch can play a significant role in a trees life. The pro arguments are: stop other plants from competing for water, maintaining ground temperatures. The only issue I have now is my mower grabbing the mulch around the outside mulch Ø. I'm going to put metal landscaping edging around the cirlce, which will be about 20'. http://dallastexas.ezhoster.com/GIRDLED_MATURE_TREE.html

    I'm curious to know what others think of a big mulch diameter.......

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  25. I like this concept, however my trees are yet saplings and I'm using mulches to protect the drip watering system ran to every tree we've planted. but yes, in 3 to 5 years, all that will be gone as the saplings will have survived it's initial growth and established sound roots. at that point mother nature will be allowed to reclaim her territory.

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  26. So first time home buyer... My wife loves trees. Do you think this would be a good idea if I want to put some in the back that she can watch grow over the years? I have a tree service in Calgary coming by to surprise her for her BDay. Yes no? Maybe so? Any info or feedback would be great!

    ReplyDelete
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