How to Burn Out Tree Stumps

How to Burn Out Tree Stumps

I have tried out quite a few methods of trunk removal, and each comes with its own issues. I think the one I found to be the most labor-intensive was using only a shovel and a tunneling bar and working at removing the stump for weeks. The method of stump removal I found the most fun was wrapping chains attached to a winching bar on a truck to the stump and popping it out of the ground in one quick jerk.

Other methods of stump removal, like using a stump grinder and stump burning, fall in the middle of the labor/enjoyment matrix.

When it comes to cost, stump burning is probably the cheapest method but is not advisable in every climate at any time of year. As with any fire or high-temperature work, you need to make sure there are no fire bans in effect in your area and that the weather won’t dump a ton of water as soon as your stump is burning. If you are intrigued by stump burning, then read on to learn all that you need to know about this effective stump removal process.

How To Remove a Tree Stump by Burning?

Before attempting to remove a stump with fire, the proper steps need to be taken to ensure you can complete the job and do it safely. Before starting, gather everything you will need to see the job through, including but not limited to eye protection and safety gear, flammable substances, fire starter, and additional fuel sources, as well as anything needed to extinguish a wayward flame or an out-of-control burn.

Once you have what you need and are working within a safe, clear 24-hour window of weather, you can proceed with the wood-burning option.

Dig Down to Expose the Stump

Tree Stump

Using a shovel or tunneling bar dig down as deep as you can around the base of the stump. If you can remove the soil and reveal the root systems, you will have a better chance of burning the entire stump that remains below ground as well as what sticks up. Bank the dug-up soil near the trunk so you will have access to the dirt needed to extinguish the flames and to fill the hole back in when the burned-out stump is removed.

Remove Nearby Combustible Materials

As you are digging and getting the area around your stump ready, you will want to remove any combustible materials like dead leaves, wood mulch, or sensitive plants. You can also use fire-resistant materials to block things like structures and fences that could be in danger of catching fire if exposed to flames for too long.

To help increase the safety of the operation, you can also use a garden hose to spray down the area outside of your burn zone to keep moist soil, stopping embers from spreading.

Remove Toxic Plants and Materials

Some plants produce toxic fumes and noxious gases when they are burned. Unfortunately, a lot of the plants that do this grow as understory plants to help keep trees healthy. If the tree died but the shrubs survived, check to make sure they can be burned safely in case the fire spreads to them.

If they are oleander plants, Mexican elder, or anything called “poison” or “deadly”, you will want to relocate them before starting your fire. 

Drill Holes into Stump and Roots

Using a 1-inch spade drill bit, drill 10 inches deep into the top and sides of the stump. If it is a dead stump, this will be easy, but a green stump may take some work to drill completely into. Make sure the drill holes are as deep as you can go so you will get full penetration of the chemical accelerant. Clean out the holes with an air gun or compressor to improve the absorption of the liquid or powder accelerant chemicals that will be poured in using a garden trowel and funnel. 

Add Flammable Materials

The best way to increase the speed of stump burning is to get flammable materials into the holes you drilled and let them distribute throughout the pesky tree stump. Not all flammable materials are equal, and fire starters like lighter fluid, gasoline, or other explosive chemicals shouldn’t be used. Instead, use things like kerosene, potassium nitrate, saltpeter, or other controlled chemical accelerants.

Place them in the holes you drilled and allow time for wet chemicals to absorb. If using powder fire starters add hot water to the holes and allow time to sink into the root system.

Place Firewood

Next, you can surround the stump with charcoal and then build a fire teepee with dry scrap wood and firewood. Keep a bucket of water on hand and have a water hose available in case things start to get out of hand. Makes sure there are gaps for air to get around the dry wood so the fire can burn long and hot and achieve smoldering of root systems. Place kindling and other fire-starting material inside the stacked sticks.

Start the Fire

Using matches or a grill lighter, light the kindling and let it burn. Don’t use lighter fluid or gasoline to start the fire, and build it safely and slowly until the kindling and piece of scrap wood catch fire. Once the fire starts, control it and make sure it stays around the stump. A living stump will not ignite as quickly as a partial stump or a dead stump, so be patient and keep building the fire.

Keep Fire Going

The fire has grown, and the charcoal and accelerants have caught fire; you can continue to add dry wood on top to keep a steady blaze. You should aim to treat the above-ground fire like you would a campfire keeping it hot but not too tall or out of control. This will require regularly adding new combustible materials to fuel the flames and will keep you tethered to the job for many, many hours.

Monitor The Fire

A stump fire will likely burn for 12 to 24 hours and can last several days for larger tree stumps. At no point should the fire be unattended, which is what makes this removal method tricky. Either you or someone responsible enough to safely handle a fire will need to be on hand the entire time the stump is burning to add fuel and control any wayward flames or jumping sparks.

Failure to monitor your fire could result in the flames going out, and only some of the stump burning or an unintended fire spread that could become a potential legal and safety nightmare. 

Remove the Burned Stump

Once the fire has burned down and the heat has receded, you can finish the extraction process. Any parts that are not ash can be easily removed with a shovel and placed off to the side. If you want, you can refill the hole with the soil you removed before. Depending on what you want to do with the space, you can add more soil additives and plant a new tree or level the area and cover it with sod or your ground cover of choice.

Stump Burning Techniques

While the end goal of burning out a dead stump and unwanted root system remains the same, the exact way you go about it can change. There are several different chemical accelerants that can be used to help the fire reach deep into the tree’s root system. Which one you choose and how you prepare your stump can impact the exact type of burn you will have, and so some consideration is warranted. 

TechniqueType of Accelerant Benefit
Kerosene LiquidThe liquid burns stably and for a long time and will penetrate deeply into the wood
Potassium NitratePowderReadily available and can be found in high-nitrogen fertilizers 
CharcoalChunksSmall pieces can wedge under tree roots, and larger chunks will stay ablaze for many hours once lit
SaltpeterPowderCheap and abundant breaks down naturally and can increase penetration when followed with warm water

Liquids 

These accelerants are nice because they only need to be poured once and will be absorbed by the trunk and roots on their own. Kerosene is the most common liquid accelerant for tree stump burning as it burns more stably than gasoline and diesel. Make sure to use the correct amount of liquid accelerant for the size trunk you need; otherwise, you may build too big a fire or one that cannot kill the entire root system.

Powders

Powders are cleaner to work with but need to be carefully poured in and shouldn’t be applied when the weather is windy. Powders will not penetrate without additional water but can create a lot of heat and sustain fire in the roots for a long time once properly incorporated into the wood. 

Charcoal

Charcoal has the benefit of being crushable and able to be built up and topped off as needed. Smaller pieces of charcoal fit under pieces of root and will burn for a long time once ignited. Larger chunks of natural charcoals and briquettes can be piled high and left to burn for days, creating the required heat to tackle any size trunk. Charcoal produces a lot of smoke, so other options may be better if that is a concern of yours. 

Reasons to Burn a Tree Stump?

Burnt Tree Stump

With all the fire safety warnings and things we learn not to do, lighting a tree on fire sits pretty high up there. But there are reasons to do it and if you find yourself needing to burn your stump, then having the right resources to do it safely is crucial. If you have any of these issues or problems, then burning the tree stump might be your best bet. 

Don’t Have a Grinder

Stump grinding can cost a bit of money, especially if you don’t happen to own or know how to use one. While renting isn’t terribly expensive, it will probably cost you more than $100 to get it to your place, plus the time and effort of removal. If you need to hire a fully professional service to actually do the work, it will cost even more. Save time and money and just burn the stump. 

Termite Danger

Sometimes old dead stumps are the perfect breeding ground for termites. Even if you grind or pull up the stumps, you will most likely miss a large part of the colony. Burning the stump will ensure that any pests living there will be cooked to a crisp as well. You will destroy any termites, ants, or invasive pests that were living in the old stump.

Too Hard to Dig Up

Sometimes stumps are in places where it will be hard or even impossible to dig up. A controlled burn may do the trick and get you out of a tight jam. For trees in really precarious places, you can consider placing a metal drum or other fire-resistant material around the stump and doing the burn inside. 

Want to Keep the Biochar

The process of burning wood for several hours can produce biochar which is a great soil additive. If you burn a stump instead of removing it, all of the nutrients produced can be incorporated into the soil and used to grow a new tree or other plants on the spot of the old tree. This is the way indigenous groups sustainably managed forests before colonization and logging began clear-cutting and less sustainable tree removal activities.