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It’s smelly. It can contain wire. It doesn’t break down. All are partially true statements when talking about rubber mulch, but there are good uses for this relatively new product as well.
According to the Rubber Manufacturers Association (RMA), of the 270 million scrap tires generated annually, at least 15 million are processed into ground rubber, or "buffings." These buffings are what is used to make the rubber landscaping mulch you've probably seen for sale recently in home improvement centers.
Several companies are now in the business of making rubber mulch and offer it in a variety of colors, including green, blue, black and terracotta. You can find it in either chunk or chipped form. Popular brands include American Rubber Technology's Rubberstuff® and Dupont's Garden Products Long-Lasting Mulch.
So what are the claims being made about rubber mulch and how does it compare to wood mulches? Here are some pros and cons:
Pros:
Won't break down and in most cases is guaranteed to last 10+ years
Won't float or blow away
Is non-porous, so water and wet fertilizer applications will pass right through to the soil below
Suppresses weeds
Can be used against the house, thus discouraging wood-eating insects
Non-toxic and non-flammable
Cons:
Does not add organic matter to the soil
Landscaping grade rubber mulch can contain wire
Costs more (initially)
Can be smelly for a brief period upon application
Some of the "pros" listed above are not without controversy. There is concern that rubber mulch does indeed leach zinc into the soil in small amounts and can cause an imbalance in soil alkalinity. A few gardeners have reported that after rubber mulch was placed around landscape plants, the plants died.
I'll have to admit I was wary about this stuff. However, my mind was changed somewhat after a dilemma I faced with my sunroom.
I have a "live" solarium in my house; that is, there are palms and other tropicals growing right up through the floor around the border of the room. For many years, this area was mulched with standard wood chips.
Well, after awhile the wood mulch started to break down, as it should. That's fine if you're outside. But indoors, the gases released by decaying mulch can be smelly and harmful. So I figured...what about this rubber mulch thing?
I wasn't terribly concerned with enhancing the soil quality - it's mostly builder's sand underneath and the plants seem fine with that.In this case, rubber mulch was the perfect answer.
After scraping off what was left of the old rotted wood mulch, I bought four bags of Rustic Red Rubberstuff® and applied it. And I must say, it looks good, doesn't smell and seems to stay put (except when my collie decides to do some digging.) The mulch has been in place for about six months and my plants do not show any ill effects.
As an organic gardener, I'll probably never use rubber mulch in my yard. Although it apparently does eventually break down after 25 years or so, I just don't like the thought of all that rubber (and some wire) being in the soil that I've tried so hard to improve by natural means.
That's not to say rubber mulch isn't handy for some tasks. The wire-free type is currently being used by many schools and municipalities for the surfacing of playgrounds. It is also gaining popularity as a softer surface for sports fields, military training bases and equestrian arenas. The question still remains about leaching, however. Are our waterways being polluted? Is the soil becoming unbalanced?
Weigh the pros and cons for your own landscaping needs, but know this: we'll be hearing more about rubber mulch in the future, one way or another.
About Tamara Galbraith
I am an avid organic gardener and certified Master Gardener for Collin County, Texas (that's North Dallas).
Despite those lofty titles, I still manage to kill stuff on a regular basis. My gardening experiences are periodically chronicled on my blog at: http://can-u-dig-it.blogspot.com
Posted by MorgaineChya (from Arroyo Grande, CA) on July 18, 2008 at 06:38 PM:
I am a conservation specialist for a government agency. As part of my job, I analyzed the suitabilty of an artifical turf rebate program for our customers. I believe the findings on artificial turf can be applicable to rubber mulch. They are both made from old tires, and the issues of toxic dust and runoff are similar.
The following is from the section on what you should do if your kid plays on artificial turf:
.****(BEGIN QUOTE)
· Children ages 6 and younger are most susceptible to lead’s harmful health effects. To protect the public, in particular young children, consider posting signs indicating that:
1. After playing on the field, individuals are encouraged to perform aggressive hand and body washing for at least 20 seconds using soap and warm water.
2. Clothes worn on the field should be taken off and turned inside out as soon as possible after using the field to avoid tracking contaminated dust to other places. In vehicles, people can sit on a large towel or blanket if it is not feasible to remove their clothes. These clothes, towels, and blankets should be washed separately and shoes worn on the field should be kept outside of the home.
3. Eating while on the field or turf product is discouraged.
4. Avoid contaminating drinking containers with dust and fibers from the field. When not drinking, close them and keep them in a bag, cooler, or other covered container on the side of the field.
***(END OF QUOTE)
It is notable that, in response to the CDC's advisory, San Diego has stopped its rebate program for turf removal and replacement with artificial turf.
An issue not yet addressed by the CDC is the high incidence of MRSA infections associated with artificial turf.
The issue with MRSA is that, unlike grass turf, artificial turf is not cut off and not regularly irrigated. Therefore, contaminants, including blood and body fluids of players, accumulate, including infectious body fluids. The artificial turf industry has come up with bacteriacides for drenching the artificial-turf fields, but then that brings up the additional issues of player exposure to the bacteriacide residues, toxic runoff, and breeding up more resistant forms of MRSA.
Artificial turf contains heavy metals. The metal of focus by the CDC is iron, but notably cadmium and zinc are also found. As the product degrades, these heavy meals are released and can cause toxic damage to our environment. According to OSHA, it takes very little cadmium exposure to cause health problems.
I would strongly advise those considering use of rubber mulch in their landscape to take into consideration the leachate produced by them and especially the risks if it is exposed to flame. One thing not addressed by the discussion of fire risk is the issue of exposure to toxic fumes should it catch fire. Fires from rubber tires produce very toxic fumes. It would be logical to surmise that fires from products of rubber tires would also produce very toxic fumes.
As far as using it on a playground or othe child-playing surfaces, I would recommend that parents review the CDC's information on steps recommended should a child play on artificial turf. Clearly, there is a high level of toxicity involved, especially for children who have less body mass and so are often impacted more severely from exposure to toxins.
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Posted by TexasTam (from Plano, TX) on June 04, 2009 at 06:09 PM:
More follow-up news concerning the safety of rubber mulch:
Posted by mamoriah (from Maitland, FL) on May 29, 2008 at 10:14 AM:
Thanks for the well-balanced approach!
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Subject: Rubber Mulch
Posted by mythmkr (from Wichita, KS) on May 26, 2008 at 11:18 AM:
T,
I found the rubber mulch at Sam's and took a chance with it. I used it in an area where there will be "no Growing" to cover a mud area-wide pathway to get to my potting shed.
I love it, it works and what I bought has no ordor. It has saved me countless hours cleaning up my garden clogs etc.
The problem is, I need 4 more bags and Sam's is now sold out in my area.
It works for me but I wouldn't use it in and around my garden.
Connie in Wichita, Kansas
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Posted by TexasTam (from Plano, TX) on May 26, 2008 at 11:41 AM:
Hi Connie!
I agree - rubber mulch has its uses...but not in my garden!
You might try to find the same or a similar rubber mulch at Home Depot or Lowes. Both of those in our area carry many different colors and brands.
Thanks for writing,
TexasTam
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Posted by Napergal (from Naperville, IL) on May 26, 2008 at 04:06 PM:
I am seeing this product being used under playground equipment ...cushions the little tykes' falls quite nicely!! I think it would be great for jogging tracks, pathways, etc. and it certainly keeps all those smelly tires out of the landfills and from being piled up somewhere where they can catch on fire and burn for years!! I am a bit worried about using it in a garden setting, though. I imagine it gets very hot in the sun (like your tires do on a summer day!!) and could burn delicate plants, and we have no idea what it leaches into the soil, do we?
Sandy
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Posted by orchid923 (from Indian Harbour Beach, FL) on May 27, 2008 at 06:51 PM:
Our University of Florida IFAS Extension office in Brevard County, FL doesn't recommend it. The leaching of zinc for one thing and difficulty in getting concise information from the manufacturers regarding what exactly is in that rubber mulch (apart from the wires). Perhaps just using it in a path area might be OK. I don't think it should ever be applied in a children's playground area until more is known about it (remember the treated wood that was used in children's playgrounds years ago ?).
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Posted by knapp1 (from Richlands, VA) on March 24, 2009 at 09:08 AM:
Can rubber mulch be used around spring bulbs (Tulips, Daffodils, etc.). What about perennials that die back in winter and emerge in spring? Will the plants be able to penetrate the mulch next year?In other words, If I put it around my blooming flowers now and it suppresses the weeds will it also suppress my flowers when they attempt to emerge next spring?
knapp1
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Subject: Informative article!
Posted by joegee (from Bucyrus, OH) on May 24, 2008 at 03:04 AM:
I have wondered about this product myself. What has kept me from purchasing rubber mulch was the experience of a local scrap yard that underwent a massive tire fire. The byproducts not only leached into the soil, they also contaminated local streams and caused an expensive cleanup that has yet to be finished.
If this mulch burns, my understanding is it will convert into petroleum-like products including asphalt. In quick research I found this article which talks about the flammability of commonly-used mulches http://findarticles.com/p/articles/mi_qa4107/is_200311/ai_n9... . Rubber mulch was the most flammable mulching material.
"Decorative ground rubber ignited each time it was exposed to the propane torch and produced spreading flames in 60 seconds. Ground rubber always had to be extinguished by the investigators (Table 2). The flames often spread rapidly and were extinguished with difficulty. Decorative ground rubber is sometimes recommended for use in playgrounds to cushion falls, but in our judgment is far too easily ignited for this use. The article "Playground Fires Tied to Cigarettes" reaffirms our concern (Playground Fires 1997)."
There's much debate, but thank you for the excellent article!
-Joe G.
This message was edited May 24, 2008 3:11 AM
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Posted by gardenpom (from Melbourne, FL) on May 24, 2008 at 07:02 AM:
Enjoyed your article....I doubt I would ever buy this stuff myself, but as you say, there are some good uses for it. For my yard I prefer the wood mulches.
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Posted by lakesidecallas (from Dandridge, TN) on May 24, 2008 at 09:14 AM:
Good article, thanks.
This message was edited May 24, 2008 8:14 AM
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Posted by terichris (from Naples, FL) on May 24, 2008 at 09:34 AM:
I used two bags of rubber mulch in the bare grass floor of my children's playhouse. We started with regular mulch & the kids were filthy! This seems to have done the trick. I don't use it in the gardens though. I am not sure what that says about me - its ok for my kids to be playing in it, but I don't want it on my plants. Hmmm, perhaps I should rethink this...Thanks for the article.
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Posted by MistyMeadows (from Payneville, KY) on May 24, 2008 at 12:04 PM:
Only just heard about this for the first time last week. I do have a concern about what will be leaching out of the tires, not to mention oils that are in the tires. It will be interesting to see what eventually comes from reports of this.
This message was edited May 24, 2008 12:05 PM
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Posted by jojoringer (from Joey in Conroe, TX) on May 24, 2008 at 01:16 PM:
Great article. I haven't used it but had neighbors that did. In our humid climate, the soil never dried out and almost everything in the garden succumbed to fungus and mold (a constant battle here anyway). When they pulled it up it was downright slimy underneath. That was enough for me LOL.
I had thought of using it for pathways, but hadn't thought about the leaching factor, thanks so much for the heads up!
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Posted by cathy4 (from St. Louis County, MO) on May 24, 2008 at 02:10 PM:
A timely article as we are trying to decide what to use under the grand children's swing set.
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Posted by carrielamont (from Milton, MA) on May 24, 2008 at 05:06 PM:
Good to learn about - we are always buying mulch, often the wrong color or kind (whoops) so it's good to be aware there will be more to confuse us! Thank you, Tammy.
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Posted by MargaretK (from PERTH, Australia) on May 26, 2008 at 06:09 AM:
If the rubber mulch leaches zinc, it would probably benefit our zinc-deficient Australian soils. Even so, I'd be reluctant to use it on the garden.
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Posted by DeenDixie (from Fayetteville, AR) on May 26, 2008 at 11:17 AM:
An informative article... thank U. I saw this stuff for the first time yesterday when I was at HomeDepot looking for compost...I read the package details and immediately recoiled. Lord knows, we desparately need useful alternatives for old tires, but I would prefer to fall over and die rather than put this stuff on my beloved garden. Kindest regards....
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Posted by ccove (from West Islip, NY) on May 27, 2008 at 10:27 AM:
I recent article here in NY, was questioning if there was a problem with lead leaching. Not having his mulch I didnot investigate it. You can find it in the archives of Newsday if you are interested.
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Posted by DouginMtVernon (from Alexandria, VA) on May 28, 2008 at 11:15 AM:
I will drop dead before I ever spread anything like shredded rubber on my garden or ANYWHERE for that matter!
I vehemently disagree--there is NO SUCH THING as a good use for this product!!! This is not natural and not even good for playgrounds---do you want your small children running and rolling around on products whose safety is not known?
No, thanks. All stores that carry this product ought to pull it off the shelves immediately. Disgusting.
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Posted by TexasTam (from Plano, TX) on May 28, 2008 at 01:46 PM:
Well, I knew this article would cause some controversy...!
DuPont claims its product "meets/exceeds American Society for Testing and Materials (ASTM) standards for safe playground surface use." Not sure about the others. I know some brands claim to be thoroughly washed and 99.9% wire-free.
In the end, I'd prefer a good and safe use was found for this stuff rather than seeing all those tires ending up in the landfill...
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Posted by joegee (from Bucyrus, OH) on May 28, 2008 at 02:30 PM:
Rubber mulch from a reliable manufacturer sounds excellent for inside applications where the look of mulch is needed without a material that holds onto mold. I'd wager it rinses off very well, and probably disinfects easily. I remember we had a planter inside my first home that my parents filled with gypsum rock. This mulch would work very well there.
I'd say a lot depends on the manufacturer.
As with any product it pays to be aware of the potential risks involved with it.
Again, thank you!
Joe G.
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Posted by DouginMtVernon (from Alexandria, VA) on June 27, 2008 at 03:10 PM:
And anyone who takes such claims as "meets/exceeds American Society for Testing and Materials (ASTM) standards for safe playground surface use" directly from a manufacturer is simply risking their own skins.
Come on, in today's regulatory environment which is DECADES behind detecting and abating the real threats to humans in consumer products, do you REALLY trust the manufacturer's word?
And in this political environment, what cost is their to a company who may not be completely upfront about risks, known or unknown?
Gardening is a natural activity. Shouldn't we as gardeners be keeping it that way? Just my 2 cents. I find products like this morally reprehensible and irresponsible.
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Posted by DouginMtVernon (from Alexandria, VA) on June 27, 2008 at 03:12 PM:
Oh yeah, and these days, 100% of tires are RECYCLED! That's a far better use than spreading the material in any area designated for natural uses that are exposed to humans, indoors or out.
After scraping off what was left of the old rotted wood mulch, I bought four bags of Rustic Red Rubberstuff
