A sad fact of life is that sometimes a tree must be cut down. Some trees are beset by invasive insects or disease, others may be mangled by storms, and some die from environmental stress or old age. Once the tree is removed, we are often left with a stump. Which leads me to a popular question: “What can I do to get rid of a tree stump?”
The internet is full of tricks for dealing with tree stumps. Some sound practical, while others seem dangerous. Let’s examine some common tree stump removal techniques. First will look at techniques for physically removing the tree stump and then ways to treat the tree stump in place.
Physical Removal
Hand digging or grubbing
For smaller trees, it is possible to dig them out by hand. While some information specifies trees with a 15-inch trunk diameter or less can be hand-dug, I personally wouldn’t go much over a 6-inch trunk diameter. That’s because digging out a tree is hard work, but with enough time, leverage, and pain relievers for a sore back, hand-digging a tree stump is an option.
Using an air spade or high-pressure water can help excavate soil around the roots to assist in cutting the roots and extracting the stump. High-pressure water can be quick, but a plan must be in place to handle the pooling water and mud. Saturated soil can make it difficult to gain leverage to remove the stump once it is severed from the root system. Vacuum trucks or digging a system of temporary slopes and trenches can be used to move the mud and water away from the stump. Air spades work in a similar manner to high-pressure water, but instead of mud, you now have dust to contend with. Protect your eyes, lungs, and hearing when using an air spade. A commercial-sized compressor is often necessary for running an air spade. Erecting a type of barrier or shroud is recommended around the stump for both high-pressure water and air spade techniques, so mud or dirt is contained.
Mechanical Removal
Pulling, pushing, or digging out a tree stump is made far easier with machinery. However, this adds additional equipment cost and potential damage to the surrounding landscape. Machinery needs a place to operate, and depending on access, may require disrupting adjacent parts of your yard.
Digging up tree stumps with specialized equipment can be accomplished using backhoes, excavators, or loaders. This process will easily sever large roots in the ground, making it easier to remove the stump.
Stump pushing usually involves a heavy tractor with a blade that pushes over a tree stump. Pushing over tree stumps is usually done in land-clearing operations where there is plenty of room for large equipment to operate.
Stump pulling uses heavy equipment along with cables, winches, and pulley systems to drag a stump out of the ground. The internet is full of online videos where people try to pull up tree stumps with vehicles, only to be met with a pricey auto repair. According to Dr. Kim Coder at University of Georgia’s Warnell School of Forestry and Natural Resources, a half-inch diameter root requires 450 pounds of force to pull from the soil. And for larger trees structural roots coming off the base of a tree stump can far exceed half an inch in diameter.
To make stump pulling easier, saturating the soil surrounding the stump with water will help, so long as you are not also saturating the soil where the equipment will be.
Regardless of whether you dig up, push, pull, or use a combination of those methods, the tree removal crew will need to leave a taller stump of several feet for better leverage.
Treating the Stump Onsite
Stump grinding
Many tree companies offer stump grinding as an additional service charge when removing a tree. Various types of stump grinders can remove stumps to a certain depth, ranging from flush to the soil line to over a foot deep. Often, the deeper you want a stump ground out, the more it will cost you. Depending on how far down a stump is ground, you may be left with a large hole. If planting turfgrass where the former tree resided, it is recommended to haul off the chipped stump debris and fill the hole with quality topsoil.
Typically, the grindings from a tree stump get mixed in with the surrounding soil as the blade chews up the stump. Wood material mixed in with the soil can tie up nitrogen as the wood breaks down, making it difficult to grow lawn, or another plant where the tree once stood.
Burning
Stumps can be burned out, however, be sure to check your local ordinances to see whether open burning is permitted. Because stumps are buried in soil, drying the wood enough so it will burn can be difficult. Avoid pouring fuel on a stump, which can contaminate the soil.
Instead, create a “stove” of charcoal on top of the stump using a metal cylinder with no top or bottom. A stump fire will burn hot and possibly for many days. High heat can sterilize the surrounding soil, making it difficult for future plants to grow.
While burning can quickly break those strong bonds of the stree stump and release that energy into the atmosphere, charred remains that may be left behind of the stump are inhospitable to decay microbes and will resist further breakdown.
Digging around the stump to expose it to air can help in drying and providing oxygen for burning. Sometimes chemical pre-treatment to stumps (described in the next section) is suggested prior to burning. However, in some locations, this practice is not allowed.
Chemical treatment
Unfortunately, chemically treating your tree stump will not liquify it overnight. Often, what is applied are salts to break down the tough woody material, but it is also detrimental to the living decay organisms that decompose tree stumps. A common ingredient used in stump chemical treatment is potassium nitrate also known as saltpeter. The salt pulls out water from the stump, which can help dry it faster for burning. Follow the label directions when using chemical stump treatments.
According to Dr. Coder, chemical treatment speeds up decomposition by about 25%, whereas enhancing natural decay (by increasing surface area, soil aeration, moisture, and nitrogen availability) can accelerate degradation by up to 50%. How quickly a tree stump decays depends on size, species, the date it was cut down, and many other site-specific features such as sun, drainage, soil biology, etc.
Steps to enhance stump decay
Increase surface area
While it can take years for a tree stump to naturally rot we can help speed things up a little. The first step is to cut the stump as low as possible. Next we need to create as much surface area as we can for the decay microbes to start feeding. Drill several large holes using a 1-inch bit in the top and side of the stump. Any majors roots that are exposed can also have holes drilled into them. Use a saw to rough any wood glazed smooth from a saw or stump grinder. Cut criss-crosses in the stump. The more gaps, cracks, and holes, the better. Cut and peel off as much bark as possible.
Aerate the soil
The decay microbes we want eating the tree stump are adapted to atmospheric oxygen levels. As wood rots, it releases carbon dioxide which needs to be replaced by oxygen to keep our little critters going. Aerate the soil around the stump using augers, hollow-core machines, or a tiller going as deep as you can, with the recommended depth being 12 to 24 inches. You will hit roots and that is okay, provided they are the roots of the dead tree.
Manage the soil moisture
Wood submerged in water rots very slowly, so we need to be sure to have adequate drainage around our tree stump. While we just discussed the need for aeration, air dries out the soil, so we must balance the moisture levels with our need for oxygen. Irrigate the stump frequently, so long as the spot does not hold water. Covering the stump with a coarse wood mulch can help insulate and hold moisture.
Add Nitrogen
Wood material is, at a basic level, a complex block of sugars woven together. To break apart that block of sugar requires microbes fueled by nitrogen. Nitrogen can be found throughout the environment, even in the stump itself, but because every living thing uses nitrogen, it is often the most limiting element.
Most stumps will have a low nitrogen content and to minimize this constraint, additional nitrogen fertilizer can be applied to the stump and immediately around the stump. Slow-release fertilizer with a low salt content is recommended. The amount of nitrogen depends on the size of the tree stump. Dr. Kim Coder suggests for a 10-inch diameter tree stump apply 0.5 pounds of nitrogen annually. It is suggested to split the 0.5 pounds of nitrogen into three applications to the stump over a year. Do not apply more than 7 pounds of nitrogen in any one application.
Inoculate
More than likely, if your soil grew a large tree, it has everything needed to decompose the remains. In some harsh soil conditions, it can be helpful to spread a thin layer of healthy soil around and on top of the stump. Healthy soil or compost, has decay organisms that can be used to inoculate poor soil.
Protect the stump
Installing some type of covering over the tree stump can help minimize water loss and shade microbes from the sun. Geotextile or landscape fabric are materials that can be used, but avoid plastic sheeting. We want a permeable covering to exchange water and oxygen from the soil to atmosphere. However, it is my opinion that if you have a thick layer of woodchips, this can suffice as a covering.
Add sugar…yes, you read that correctly
Over time, as a stump decomposes, the microbes will consume the carbohydrates (sugar), leaving behind tough lignin material. This is when stumps have lost 1/5 to 1/3 of their total mass. At this point, sprinkling granulated sugar on an older stump will help the decay process continue.
Continued Disruption
Like a compost pile that requires turning, going in and stirring things up a bit around the stump can help push along the decay process. About every three months go back in to cut, drill, scar, tear with a pry bar, anything to keep beating up the tree stump will increase the decay rate.
Do nothing
This is an ecologically valuable option. Dead trees are tough to find in a developed area and can be a refuge for wild animals. If you can leave a dead tree, then do it! If you must cut it down, but can leave a tall stump, then leave a tall stump. If you can’t leave a tall stump, but perhaps a shorter one, then do that. Dress up a stump as a fairy house or add containers of flowers.
The energy locked up in a decomposing tree stump becomes an oasis for life. As the stump decays through time, the composition of organisms shifts as the former tree is eventually returned to the soil to sustain the next generation of trees.
Blow it up!
In bygone years, explosives were commonly used to remove tree stumps. Blasting or blowing out a stump using TNT was an important tool before we had modern heavy equipment. Human nature of using more than needed has not changed much, as there are many stories of over-charging explosives, which would fling debris well beyond the tree stump location.
While explosives successfully shear off roots and elevate the stump for easier extraction, it is really not practical in our modern communities. Many utilities are buried beneath the soil that can be impacted by an explosive charge, not to mention nearby building foundations. Blasting the soil also creates a compaction layer beneath where the explosive was detonated. Today, using explosives to remove a tree stump would require specialized training and being a certified explosives expert. This technique is included as a glimpse of what used to be done, not a recommendation of how to remove a stump today. But if you want to hear more about the historic use of TNT in the landscape, we talk about that during our Good Growing podcast episode about old-timey garden remedies.
Good Growing Tip of the Week: Uh oh, is your tree stump resprouting? If a live tree is cut down, often it will resprout from the stump or the surrounding root system. For live tree stumps, while the cut is fresh, treat the outer sapwood with a systemic herbicide containing glyphosate or triclopyr.
An excellent source on tree stump removal, which was referenced extensively in the above article: Tree Stump Removal in Landscapes, by Dr. Kim Coder, University of Georgia, 2021.
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MEET THE AUTHOR
Chris Enroth is a horticulture educator with University of Illinois Extension, serving Henderson, McDonough, Knox, and Warren counties since 2012. Chris provides horticulture programming with an emphasis on the home gardener, landscape maintenance personnel, and commercial landscapers. Additional responsibilities include coordinating local county Master Gardener and Master Naturalist volunteers - providing their training, continuing education, advanced training, seasonal events, and organizing community outreach programs for horticulture and conservation assistance/education. In his spare time, Chris enjoys the outdoors, lounging in the garden among the flowers (weeds to most).