Factors Causing Mulch Fires - National Association of Landscape Professionals

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Factors Causing Mulch Fires

Spring mulching season has been well underway over the past month or so. Your customers appreciate a good quality mulch that improves the overall look of their home’s landscape. But keep in mind several simple rules to prevent mulch from smoldering, catching fire, and potentially resulting in considerable damage to residences and buildings.

Excess Mulch Factor

Mulch heat is generated through the process of organic material that is naturally decaying. The general rule of thumb is to avoid thick layers of mulch by applying less than 6 inches, and more preferably within a range of 2-4 inches to prevent excess heating.

Fire Ignition Factor

Another consideration is the interaction between common human behavior and drying mulch near buildings. An important rule to follow is to prevent an accelerant from becoming the ignition source for a mulch fire. Carelessly thrown cigarettes and hot matches have the potential for igniting dry, hot mulch, resulting in a mulch fire that gets a good start before being noticed. Strategically placed fire-proof receptacles can prevent a serious fire loss.

Dry mulch is more likely to ignite, so a good recommendation is to keep the mulch moist. Encourage your customers to do the same after mulch installation and when your crews are not on the job site. When watering plants in mulched beds, wet the mulch thoroughly.

Fire Spread Factor

Mulch that is in close contact with a residence or other building can be a serious fire danger, especially when the building has siding that could ignite and spread quickly. If possible, it is a good idea to establish an 18-inch clearance between foundation mulch and any building.

Mulch Type Factor

Finely-textured mulch material is more likely to pack together, not only reducing the amount of oxygen reaching the root zone but also potentially raising the heating potential. This also applies to darker color mulches, so take these into account during any mulch application work activities.

Don’t forget to share these important facts with your customers to help prevent mulch fires.

NALP’s safety programs are produced in partnership with Rancho Mesa.

Sam Steel

Sam Steel is NALP's safety advisor.

One thought on “Factors Causing Mulch Fires”

  1. I might add from experience, be careful not to apply mulch over in-ground lighting fixtures.
    The mulch delivery truck dumped the load of mulch on top of a light causing a fire.

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