Is Mulch A Fire Hazard? Garden Tips 2024

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Safety should always be your number one priority but sometimes, it can be hard to know what is actually a fire hazard. Mulch is a common part of gardening, so let’s find out if it also poses a threat.

Is mulch a fire hazard? Mulch can be a fire hazard if it is made from a substance that dries out, such as pine needles or wood. If an open flame, such as a match or cigarette, comes into contact with the dry materials, a fire can start. Always wet your mulch to prevent the spread of fire or use sand or gravel mulch for better peace of mind.

Risks of using garden mulch

Fuel for fire

The most common reason why garden mulch is considered a fire hazard is that it is quite simple pieces of wood. When these pieces of wood become dry, the result is a large fuel source for the start of a fire.

A thrown cigarette, the embers of a fire, or even the spark from a lawnmower are all ways a fire can start. If these items land in wet grass, the fire won’t take hold. However, if they land on a pile of very dry wood, the result can be a large and dangerous fire.

Spontaneous combustion

A less common reason to be aware of the dangers of mulch is spontaneous combustion. The heat from the ground is trapped under the layers of mulch and if you have just the right conditions, usually very high, prolonged heat, the mulch can overheat.

While spontaneous combustion is thankfully not very common, it is something to be aware of if you live in areas that don’t get much rainfall and have very hot summers, and thus the mulch has a higher likelihood of drying out.

Mulch Fire Safety and Prevention Tips

Keep away from buildings

A remote fire on its own is a lot safer than a fire that is near a large structure, like a shed or a house. The more opportunity a fire has to spread, the more dangerous it is.

Keep your mulch at least 18 inches away from the side of a wooden structure. This way, if the mulch does catch fire, it can be put out easier before it causes more damage.

Dispose of smoking material properly

If you smoke outside, be sure to properly dispose of any cigarettes or matches in proper containers. They should also not have the opportunity to blow away after you are done with them.

Many people think sticking a used match in the ground is safe. However, if the ground is bone dry and near a fuel source such as mulch, the excess heat can be enough to start a fire.

If you do smoke, a bucket of water or sand will help suppress any extra heat.

Water your mulch

One of the benefits of using mulch is that it holds water really well and then slowly releases that water into the soil. Dry mulch has some benefits, such as protection from weeds, but is not being used to its maximum potential.

Use mulch as it is intended. Water the ground every few days or at least once a week during the peak of summer so that it never has a chance to fully dry out. Damp wood can easily stop the spread of fire.

Be aware of the wind

On a windless day, if a fire starts it will remain contained and be easier to put out. Wind fans the flames of fire, allowing it to spread much easier.

If you live in a very windy area and are going through a dry summer, then being vigilant about your mulch is even more important. Wet your mulch more often, especially before major wind storms.

Keep a water source nearby

A small fire can be doused quite quickly if you have the proper tools around. A garden hose that can be accessed next to your mulch can save you immense damage.

If your mulch is further out from your house, you may want to consider placing buckets of sand nearby as this always works as excellent fire suppression. For those that are worried about the aesthetic appeal, simply make a layer of sand around the mulch so it works as a natural barrier.

What mulch is most flammable?

Pine needles are incredibly flammable. They are small and very dry, and fire can easily spread across them.

Even if you aren’t expressly using pine needles as mulch, you may have a layer of them under a tree that is naturally occurring. Try to clean these up before the hot temperatures of summer kick in.

Cedar is one of the best types of wood to start a fire and if you have ever been on a guided camping trip, you will be taught to look for this wood to start your own fire.

While cedar mulch looks nice, it is the most flammable of wood chips. Try to avoid it if you live in an area prone to wildfires.

Finally, shredded rubber is another highly flammable type of mulch. The rubber can insulate the start of a fire and it can spread more easily.  

What mulch is least flammable?

Rock and sand are not flammable. In fact, they are often used as fire suppressants.

If you need to cover an area near the base of your home, or you live in a dry, hot climate, use rock or sand mulch instead of bark mulch.

Wood chips that have been composted won’t cause a major fire hazard if you remember to water them lightly on a regular basis. It’s also better if you choose wood chips that are mixed with compost or even biomass as this mixture is harder to catch the light.


Mulch has many benefits but it does come with some risks. Bark mulch that dries, pine needles, and rubber mulch can all catch fire if exposed to an open flame. Gravel and sand mulch are better alternatives if you live in an area with hot, dry, and windy climates.

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