Homesteading, Gardening, and Off-Grid Living

Can You Burn Old Mulch? Pros and Cons + Fire Tips

By: Zac Friedman

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You can burn old mulch to get rid of it as long as it is made of an organic material. You can burn it in an open fire or in a wood stove. Burning mulch can be a great way to dispose of it. You can even use it as fuel for heat. 

You should only burn mulch that is made from natural materials such as wood chips, bark, grass clippings, leaves, straw, sawdust, etc. You should not burn mulch made from synthetic materials such as rubber. Before burning, you should make sure it’s legal to burn where you live. It’s also important to burn safely. 

In this guide, I’ll explain when you should burn mulch and when you shouldn’t. I’ll outline the types of mulch that you can burn. I’ll also outline some alternative ways to get rid of mulch. We’ll also talk a bit about how to burn mulch safety.

Can You Burn Old Mulch: Pros and Cons and Fire Safety Tips

Burning Organic Mulch

It’s best not to burn mulch that has been treated. For example, if you have colored mulch or mulch that has been sprayed with pesticides, you might not want to burn it. It could release harmful chemicals while you burn it. 

You can burn organic mulch. Wood chips, bark, grass clippings, straw, pine needles, and leaves all burn easily. These are all combustible materials. Before burning, try to dry the mulch out. It will burn faster and cleaner that way. 

Burning mulch in a fire pit
Make sure you have a safe place to burn, such as a fire pit.

Where to Burn Mulch

The best place to burn mulch is in an open air fire pit. This is the best option if you’re just trying to get rid of it. Add a little bit at a time so the fire doesn’t get out of control. Don’t burn the whole pile at once. 

You could also burn mulch in a fireplace, wood stove, or pellet stove. This way, you can use it as fuel to heat your home. If you do this, you’ll have to add a little bit at a time. Otherwise, it will smolder because it won’t get good air contact. Add a little bit every few minutes. 

You shouldn’t burn mulch while it’s on your garden beds. The fire could easily get away from you.

Reasons Not to Burn Mulch

The problem with burning mulch is that it usually doesn’t burn clean. It smokes a lot and creates a lot of ash. This is particularly true of bark mulches.

Mulch doesn’t work well as an energy source. You’ll have to constantly feed the fire and you’ll have to clean the stove more frequently than usual. It’s more hassle than it’s worth in most cases. It may be worth trying if you have a clean type of mulch, like wood mulch without bark. 

It really only makes sense to burn mulch to get rid of it. It doesn’t work well for fuel.

Check the Local Laws Before You Burn Mulch

Before burning mulch, check the laws in your area. In some jurisdictions, burning is illegal. Usually, you can’t burn in a city.

Some times of the year, there may be restrictions on burning. For example, during the dry summer season, it’s usually illegal to burn. If you get caught burning illegally, you could be fined.

In some places, you need to get a permit to burn yard waste. 

Burning mulch
You can burn mulch as long as it is legal where you live and you burn safely.

Staying Safe When Burning Mulch

When you’re burning, be sure to do it safely. There are risks when working near an open flame. To stay safe:

  • Burn in an open area far away from any structures or trees that could catch fire. 
  • Only burn a little bit of mulch at a time so the fire doesn’t get too big. 
  • Make sure you have a fire extinguisher and a water supply nearby in case the fire gets out of control. 
  • Wait for the right weather conditions. Don’t burn in high winds. Don’t burn in dry weather when there has been below-average rainfall. 
  • Make sure the fire is completely out when you’re done. Don’t leave smoldering mulch.
  • Don’t start a ground fire. It could easily get away from you. Instead, remove it from the mulch from the soil surface and burn it in a fire pit or stove.
  • Call your local fire department if the fire gets away from you.

The Best Time of Year to Burn Mulch

Wait for the burning season in your area. In most places, there is a burning season in the spring and fall. The burning season will be during a wet time of year when the risk of wildfire is low.

You should also wait for a calm day when there isn’t much wind. This will make the fire easier to control. Burning in windy weather is dangerous. 

It’s also best to burn early in the morning or late in the afternoon or in the evening. It will be cooler during this time. It also tends to be calmer. Burning in warm temperatures gets uncomfortable.

Mulch

Benefits of Burning Mulch

  • You can use the ash as a soil amendment- Ash is a source of nutrients. It contains potassium, which is good for plants. It can also be used to modify the soil pH. Ash is alkaline. It increases the pH. This can be beneficial if your soil is too acidic. Charcoal can also be good for the soil. It can help the soil hold more moisture. It can also help kill off bad bacteria. Some ash can also contain sulfur, which can help get rid of fungi. Ash will improve soil fertility. 
  • It clears up space- If you have a pile of old mulch that you want to get rid of, burning it is a great way to free up some space on your property.
  • It’s faster than composting- If you just want to get rid of mulch, burning it is one of the fastest ways to get rid of it. Composting takes months or years. Burning takes a couple of hours. 
  • It will help get rid of pests- If your flower beds get infested with pests, removing and burning the mulch is a good option. The smoke from burning can also help repel pests. If your mulch is diseased or if it is full of mold, burning it can also be a good way to get rid of it. It can prevent the disease from spreading to other parts of your yard.
  • You can get rid of other yard waste when you burn- For example, you can burn other plant materials, such as dry leaves and weeds, with the mulch. 

Other Ways To Get Rid of Old Mulch

There are plenty of other ways to dispose of old mulch. You can compost it. Organic material degrades over time. You can use the compost as a soil amendment in your gardens. If you don’t want to compost it yourself, there are also commercial composting facilities that will accept old mulch. Check to see if there is a commercial composting facility in your area. 

You could also leave the mulch in place and simply add a layer of new mulch on top. The old mulch will eventually degrade away. You don’t have to use the same the same type of mulch. 

If you do this, you should make sure that both layers of mulch together are no more than 4” deep. If it’s too deep, mold can be an issue. It can also smother your plants by blocking air and water from reaching the soil. 

You could also put it in your yard waste or haul it to a yard waste facility. If there are no yard waste facilities where you live, you could throw it in the garbage. In some places, it is illegal to put yard waste in the garbage because it takes up space in the landfill. Check the local laws first.

For more in-depth info, check out my guide: How to Get Rid of Old Mulch.

Compost bins
Composting is a great way to get rid of old mulch

Can You Burn Inorganic Mulch?

Mulches that are made from inorganic materials should not be burned. Some inorganic mulches, like rubber mulch and landscape fabric, are flammable. It’s best not to burn rubber mulch because it will emit black smoke with harmful fumes. It’s the same as burning tires. Same with landscape fabric. It’s like burning plastic. 

Of course, you obviously can’t burn rock mulch like river rocks, lava rocks, or pea gravel. 

How to Get Rid of Inorganic Mulch

Rock mulch is usually pretty easy to get rid of. Many yard waste disposal centers will take it. You will have to find a way to haul it there or pay someone to transport it for you. Rock mulch can often be cleaned and reused. You may be able to give it away.

Rubber mulch is harder to get rid of. Yard waste disposal centers won’t want it. You can just bag it up and throw it in the garbage or haul it to the dump. It will usually end up in a landfill. Even though it is flammable, you shouldn’t burn it. It can emit toxic fumes that aren’t good for the environment or your health. 

Spontaneous Combustion of Mulch

Spontaneous combustion of mulch is possible. When mulch starts to decompose, heat and gasses can build up in the mulch. This is caused by anaerobic decomposition. In a hot and humid environment, the mulch can get hot enough to start smoldering. In the right conditions, it can catch fire.

The good news is that this only happens to large piles of mulch. You generally don’t have to worry about this if you have a small pile of mulch at home. A layer of mulch that is 2-4 inches thick won’t spontaneously combust. Some materials are more likely to catch fire than others. For example, moist hay bales can be a risk. 

Spontaneous combustion can happen at wood mills or mulch production facilities that have massive piles of mulch sitting around. They must take precautions to avoid it. They will monitor the temperature of the mulch and move it or wet it if it gets too hot. 

If you have a large pile of mulch at home, you should take some steps to avoid spontaneous combustion. Particularly if you live in a hot and humid environment. Don’t leave the pile near your home. Spread it quickly so it doesn’t have to sit in a pile too long. Alternatively, you can flatten it out so it’s not in one big pile. 

Fire Resistant Mulch

If you live in an area where wildfires are an issue, it’s a good idea to use a non-flammable type of mulch around your home. This will make it harder for the fire to reach your home. For example, if you use rock mulch, the fire would have to jump over the mulch to burn your home. This can be a good way to protect your house.  

Flammable mulch such as wood chips, pine needles, or rubber can be a fire risk. Particularly in extremely dry conditions. If there was a wildfire, the mulch could catch fire and the fire could spread to your home.

If you live in an area that is prone to wildfires, avoid using flammable material near your home to avoid house fires. In most areas, the risk of mulch fires is pretty low but it’s something to consider. 

A pile of mulch next to a wheelbarrow

My Experience

Once in a while, I burn old mulch on my property. I only burn it if there is something wrong with it. For example, I had some pine bark nuggets that had a lot of fungi growing in them. I didn’t know if the fungus would spread or cause problems for my plants so I just burned it to be safe. I replaced it with cedar bark. I usually burn some yard waste once or twice per year in a fire pit on my property. Usually, I just leave mulch in place and let it degrade naturally over time. 

Burning mulch can be a great way to get rid of it. If you decide to burn, make sure you’re only burning organic mulch. Also, check to make sure it’s legal to burn in your area. Take the proper safety precautions while you’re burning. 

Burning usually isn’t the best way to get rid of old mulch. Instead of burning your mulch, consider composting it. Mulch will decompose quickly. It is a great source of nutrients for your plants. It contains nitrogen, potassium, and phosphorus. If you don’t want to compost your mulch, you can simply add a layer of fresh mulch on top of it. Of course, you can also haul old mulch to a garden waste disposal center. 

Do you burn your mulch? Share your tips in the comments below!

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Can You Burn Old Mulch: Pros and Cons and Fire Safety Tips

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