DES MOINES – If you use leaves as fertilizer in your backyard, you might want to listen to this.
Under a perfect storm of conditions — wet weather and warm temperatures — those leaves could start to heat up, and even cause a fire. They can spontaneously combust, creating a safety hazard for homeowners.
When leaves are wet and get enough warmth from the sun, they can become dangerous. Ashy remains of leaves were found in a metro backyard over the weekend. Local horticulturist Jerry Holub says it is a result of a chemical process.
“It takes quite a bit of moisture, it takes a lot of heat, and that’s what normally will make them combust on their own, or a lot of times they’ll start smoldering on you if you get enough heat,” Holub said.
This is not too common. But it can happen — especially when a big pile of leaves starts to compost.
“Some people put them two, three, up to five foot in your backyard,” Holub said. “That’s what makes them heat up and can give you some trouble.”
The Des Moines Fire Department has dealt with this a few times in the past — most recently in September of this year, when fire crews came across a smoking pile of leaves.
“Between the heat, the moisture and the organic material, it was blackening the material, hadn’t started to burn, open burn or open flame, but it was obviously charred in the soil area,” said Brian O’Keefe with the Des Moines Fire Department.
In the worst case scenario, fires can start. But there are steps you can take to protect yourself and your property.
“Don’t store it in plastic bags where the heat can build up,” O’Keefe said.
Holub adds, “Make sure with your leaves too that you don’t put them up against your house.”
Experts say they usually see these composting issues when it is more than 70 degrees outside, so you do not have to be worried right now. But it is always a good time to compost correctly.
“Spread them out or get them so they can decay and decompose on their own by nature safely,” Holub said.
If you do notice some smoke coming out of your leaf pile, call your local fire department immediately. If you use leaves to create mulch for your garden, you should also think twice about using chemicals on them. Doing so could make it more likely for heat to build up.
