Redesigning landscape with the right mulch in the right place

Blog Post created by faithberry Employee on Sep 18, 2015

With drought on our minds in many parts of the country, mulching is something many homeowners are incorporating into landscape design with other methods to reduce water consumption.  I was looking for mulch to freshen up the yard for next year and there are so many options and colors available, making mulch shopping fun.  A great article from Mulch Masters lists some reasons to mulch:

  • Reduce surface evaporation from the soil
  • Improve water penetration and air movement
  • Moderate soil temperature fluctuations
  • Protect shallow-root plants from freeze damage and frost-heave
  • Discourage weed growth
  • Improve soil structure and nutrient availability as they decompose

Other reasons to mulch are to control soil erosion, control dust, prevent soil compaction and to create a more visually pleasing landscape design.

I remembered a Firebreak blog that a good colleague previously wrote about mulches and I decided to take a look at some of the choices out there with their flammability in mind. 

Middletown, RI FD Mulch Fire
Picture of damage to a home's front porch from the Middletown Rhode Island Fire Department

When choosing mulches close to the home, especially in wildfire prone areas, it is important to take care to make a mulch choice that will help you use less water and be Firewise. The NFPA's Wildland Fire Operations Division has developed a helpful virtual workshop on research about the ignitability of mulch.

There have been some very interesting studies about types of organic mulches and their flammability including recycled rubber.  Some organic mulch types studied in a University of Arizona research project included pine needles, bark nuggets, shredded bark, grass sod, garden compost, wood chips, and wheat straw. In this study, pine needles, straw and wood chips have the greatest flame length.  In yet another study by the University of Nevada Cooperative Extension, The Combustibility of Landscape Mulches, all of the mulches evaluated were combustible under the test conditions of dry, hot and windy weather and more than 2½ months of outdoor exposure.  The mulches in this study that produced the top 3 flame lengths were recycled rubber, pine needles and shredded Western Red Cedar.

Wildfire simulations at the IBHS Research Center demonstrate that the location of the mulch within the first 5 feet of the home that can contribute greatly to a home ignition. On the Wildfire Demonstration page of their website, IBHS states, "The mulch and vegetation in the re-entrant (interior) corner was ignited by embers, and subsequently ignited the combustible siding, resulting in rapid flame spread to the soffited eaves." The dictionary definition of a re-entrant corner is where the angle points inward. It is here where embers can easily collect and cause mulch to ignite other flammable materials, ultimately catching the home on fire.  

After doing research, I decided to use a different alternative type of mulch within the first 5 feet of the home.  Some beautiful alternative mulch choices for this area include river rock (round rock), recycled glass, recycled porcelain, recycled concrete, crushed shells, gravel, paver stones and DG (degenerated granite).  The beautiful organic mulch that is located away from my home will be kept wet and thinly spread to help prevent ignition.  You can mulch with Firewise landscape design in mind.   

It is the little things that we can do to embrace changes to the home and landscape surrounding the home that can help us have a Year of Living Less Dangerously From Wildfire. 

Glass landscaping
Image of beautiful recycled glass and rock landscaping from the Joyful Glass Landscaping website