Plant a Garden, Not a Fire Threat

Spring is in the air and the planting season is getting underway. Gardens are being planned and planted across the country, yet there is an underlying threat that is not top of mind with many – the threat of a mulch fire.

Mulch is widely used in landscapes for both aesthetic and functional purposes, and is applied frequently in spring to help slow the loss of soil moisture during the hot summer months, discourage weed growth, reduce soil erosion and dust, and maintain a neat and tidy appearance. Mulch can be made from a variety of materials including ground rubber, pine needles, oat straw, shredded bark nuggets, composted leaves, ground recycled pallets, etc. However, despite its benefits, mulch can pose a fire hazard.

Mulch is flammable and can be very hard to extinguish once it catches fire. If the mulch is in close proximity to, or touching, the side of a home, the fire could easily spread to the structure. In hot, dry weather, mulch can dry out quickly, increasing the fire danger.

According to research findings published in the Journal of Arboriculture,¹ rubber mulch ignites readily when exposed to a propane torch, and once ignited, spreads readily. In the event of a manmade or natural fire, this is a significant problem. Some organic mulch, such as shredded pine bark, typically ignites only after the mulch has weathered on the ground for six months. The study notes that fire-resistant mulches include cocoa shells, pine bark nuggets and shredded hardwood.

According to a study conducted by The Ohio State University Agricultural Technical Institute, mulches that are high in oils such as pine bark and shredded cypress bark are easiest to ignite. Dyed mulches that are processed from pallets can also readily catch fire.²

To keep mulch fires out of the landscape:

Do not discard cigarettes or other smoking materials on the ground, in playground areas, or throw them out of your vehicle.
Ensure proper clearance to electrical devices such as decorative lighting by following the manufacturer’s instructions.
Maintain a minimum of a six-inch clearance between landscaping mulch beds and other combustible items such as buildings, shrubs, etc.
Use non-combustible mulch such as rock or pea gravel around the gas meter and next to combustible portions of a structure.
Maintain mulch at a depth of no more than two to four inches to eliminate the chance of spontaneous combustion.
Keep landscaping mulch beds moist, if possible.

Following this advice will help you have a productive, and safe, garden.

¹The Ease of Ignition of 13 Landscape Mulches
²Mulch Fires Common in the Landscape