Rubber Mulch: Recycling Win or Mulch Ado About Nothing?

It’s a frequently asked question. By now most folks know they should apply much in Texas, but we frequently hear “What is the best mulch to use?” often times followed by “What about that rubber mulch?”. Are there benefits to rubber mulch? Sure! It’s a recycled product that keeps millions of unwanted tires out of our nation’s landfills. It also works to reduce evaporation (water lost from the soil) around plants & landscapes AND can even reduce soil erosion. But the benefits tend to stop there. In reality, there are quite a few concerns when it comes to rubber mulch products when compared to organic products (that were once trees) like cedar, hardwood or even cypress mulches.

Top 10 Reasons:

You Might Think Twice Before Using Rubber Mulch Products

1) It’s less effective establishing new plants (Calkins et al. 1996)
2) Less effective controlling weeds (Bush et al. 2001, 2003)
3) Reduced tree growth, and increased tree mortality (Stokes 2012) 4) Can lead to Zinc toxicity (Bush et al. 2001, 2003)

Rubber mulch on fire (
5) More likely to ignite (highly flammable) (Steward et al. 2003)
6) Attracts Cockroaches (vs wood mulches) (Snoddy and Appel 2013)
7) Decomposition of rubber means that it breaks down into unwanted products, including heavy metals and other hazardous chemicals of concern. These can leach into the surrounding soil and water. -Polycyclic aromatic hydrocarbons (PAH) such as naphthalene, phthalates, butylated hydroxytoluene, etc (Llompert et al. 2012)
8) Lacks the water holding capacity of organic mulches (DeForest 2009)
9) Those unnatural colors, reminiscent of fake plants! Ugh!
10) And Most importantly you don’t get the benefit that organic mulches have as a host to beneficial microoraganisms which help cycle nutrients and increase water uptake! (DeForest 2009)

The Dirt on Amending Clay Soils with Sand

We received a great question last week from Terry who said, “I have a huge pile of sand and a huge pile of clay-based dirt that I am going to put in my garden to raise it up for better drainage. Should I put a layer of sand down 1st and then a layer of dirt or dirt 1st and then sand or should I just mix them together?”
Many articles, books, and “experts” still recommend this practice of adding sand to clay soils and its a question we still get pretty frequently. On the surface the practice makes sense but the answer might surprise you!
Contrary to popular belief, research (University of California Agricultural Extension & the U.S. Department of Agriculture) leads us to believe adding sand to clay soil, can actually be detrimental! Remarkably, a mixture of sand to clay actually tends to pack more densely than heavy clay soil, creating an easily compactable soil that isn’t fun to garden in. (If you add a little of water you can even make your own bricks)
Adding soil amendments with organic material, such as finished compost, is my favorite method to improve both infiltration and soil structure in the heavy clay alkaline soils we typically see here in North Central Texas.
You might also consider amending with (and incorporating) expanded shale, but although it is a great product, it tends to be a little cost prohibitive on a larger scale.
Topdressing yearly with ½’ -1” of a good quality compost is a great method to improve your soil over time. Others have had success adding up to 2” + of compost and incorporating into the top 6” by double digging or even a one-time minimum tillage (over-tilling can open a whole new can of worms).
Another great soil improving practice is to maintain 2”-4” of mulch in your planted beds. Not only does mulch reduce weed pressure and maintain soil moisture, as it breaks down, the organic matter improves soil structure over time.
For more information about soil amendments, composting, proper planting, or other AgriLife recommended practices, please visit our new Water University page.
AND For more information on your soil’s texture and nutrient content/ recommendations consider submitting a soil test at

Gardening For Wildlife

As promised, for those that attended AgriLife Water University’s class “On the Wildside: Gardening for Wildlife” last night in the city of Ft Worth- here are some of my favorite resources to learn more about bringing your landscape alive!
Sign up for more fun and free classes HERE!
Gardening for Wildlife, Texas A&M Nature Guides Edition By Kelly Conrad Bender…
TPWD Texas Wildscapes Certification… Texas
Birds of North Central Texas
Butterflies of Dallas County, Texas…
Ladybird Johnson Wildflower Center “Butterflies and Moths” Database…