In the summer there are a lot of fire hazards to consider: barbecues, floral lighting, candles, fire pits, etc. We all enjoy the long summer evenings, but when the weather is hot and dry there are also risks to consider.
Potting soil might not seem like the most obvious fire hazard. It might even seem silly to say that soil can burn. But potting soil is increasingly being called out as a hazard in the summer. That's because the bags of potting soil you buy at the garden store usually contain flammable materials like wood chips, coconut fiber, bark, and vermiculite.
You may have thought about the risk of mulch burning, but potting soil can also be a concern. Here, gardening experts explain how potting soil can catch fire and the best ways to reduce the risk so you can have a safe and secure summer.
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Will the potting soil burn?
Potting soils purchased online or at garden centers rarely contain significant amounts of real soil or sand. Instead, most potting soils are a combination of different ingredients, many of which, as mentioned above, are flammable. Fire departments across the U.S. are increasingly concerned about the risks of potting soils, warning that human error or actions can have serious consequences. So if you're looking for advice on container gardening and potting soils, our expert guide has all the information you need for a fire-free summer.
Can potting soil spontaneously combust?
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“Fire safety should always be considered when gardening or landscaping, especially in dry, fire-prone areas such as U.S. plant hardiness zones 9 and above,” says landscape garden expert Sam Nieman.
It is important to highlight that garden fires are generally not the result of spontaneous combustion but are usually the result of human action: barbecue embers, candles and lit cigarettes are three common causes of fires in the summer.
“When thinking about fire safety you always need to think about the container,” says Sam. “Potting soil can contain flammable materials and poses a hazard if the container is dry in summer.”
“The chances of potting soil catching fire naturally are close to zero, but it's important to highlight the risks posed by human behaviour,” Sam adds. “Using a plant as an ashtray or placing tea lights or candles in a dry container can cause potting soil to catch fire.”
Sam Neiman
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Landscaping Professionals
Sam is a lifelong horticulturist whose passion for plants and nature is what drives his extensive knowledge and expertise in horticulture. He studied at San Diego State University, earning a degree in Finance while also founding a boutique landscape design firm, Grown by Design.
How to reduce the risk of fire in your garden
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“Potting soil can burn, especially if it's organic and made from mixed materials,” says Paul T. Karlovich, horticultural technology specialist at Sungro.
“If you leave a container or bag of potting soil out in the sun, the chances of it catching fire are extremely low,” Paul says, but it could still be ignited by an external source, such as embers from a barbecue or a lit cigarette.
“Think about it: a campfire that is out will never catch fire. The problem is that sometimes people forget to 'put out' their campfires, leaving them a fire hazard,” warns Paul. Making sure the fire is out is crucial.
“The best way to reduce the fire risk from potting soil is to keep it away from flames,” says horticulture expert Katie Sanderage. “Never use pots or containers as ashtrays – this is extremely dangerous.”
“Not only is it bad for your plant's roots, it can easily become a fire hazard,” adds Katie, “The potting soil used in these containers often contains shredded wood and possibly fertiliser, which is highly flammable.”
“If you put a lit cigarette in a pot, or a tea light or candle in a pot, it can easily start a fire. My advice is to keep fire away from containers and potting soil, and you'll avoid any danger.”
To be on the safe side, it's a good idea to keep fire safety equipment close at hand. Fire extinguishers can be ordered online from Amazon. Fire blankets can also be purchased from Amazon.
Dr. Paul T. Karlovich
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Horticultural Technology Specialist
Paul is a horticulture industry expert who has participated in numerous cultivation trials over the years, learning about methods and approaches. He holds a PhD and works for Sungro Horticulture, acting as a technical advisor for Sungro products to growers in the north central US and Canada.
Katie Sunderlage
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Plant experts and buyers
As the Operations Manager for Holland Group, Katie manages the customer service department and purchasing. Katie has been involved in the Greater Milwaukee area green industry since 2005, earning her degree in Horticulture in 2008. She has shared her love of plants working in multiple garden centers, sales positions and most recently for Holland Group's online retail platform.
Although potting soil does not spontaneously combust, careless actions can quickly lead to a fire. By following these simple guidelines, you can reduce the fire risk for your potted plants and enjoy a peaceful and calm summer. For more information on soil and compost, see our guide to reusing potting soil.
