Let’s Build Strong Foundations (We and the Trees) by Removing the Dirt on Top

You may be wondering what we and the trees have to do with foundations. For anything to be successful, it must have a strong foundation, and this is no different when we discuss tree health. While trees are amazingly resilient, many silently struggle for multiple reasons. One very common reason is how they were planted or maintained after planting.

Too often, the species being planted is being decided on by a landscape plan or consumer preference. And, while professionals always try to educate the consumer about the right tree in the right place, it all comes down to what the consumer wants, leaving us to try to maintain optimal tree health. As professionals, we have a responsibility to identify many issues and present solutions. But all too often the problem isn’t a pest or disease, but rather abiotic issues such as girdling roots, compact soil, construction damage or simply stress from being planted in an area completely unsuitable for a tree to grow. This is where the importance of a strong foundation enters the picture.


Let’s first talk about mulching habits. For some crazy reason, excess mulch, aka volcano mulching, has become common. Why in the world did this happen? I’d love to know the answer to that, but in the meantime, this practice is slowly killing trees. How? Mulch – good organic mulch – is meant to provide organic matter that, as it breaks down, becomes a food source for an incredible biodiversity of organisms in the soil. That biology, in turn, has a synergistic relationship with the tree. The tree has its needs and sends signals to the root zone. That message is relayed through the roots into the soil. The biology makes the nutrients available to the tree.

What an amazing community with such an abundance of diversity that continually works together to provide immeasurable benefits to us and our planet above ground. Of course, there’s a lot more detail that could be provided here, but let’s focus on foundations first.

If the mulch is installed too thickly, it creates a barrier, and that barrier can prevent oxygen and water from getting to the critical root zone. Have you ever tried to move some mulch and it breaks up in big chunks and the underside has a white something? This is a key indicator of the barrier and of actinobacteria that indicates the environment beneath is becoming anaerobic. When the area becomes anaerobic, nothing can grow or function properly. The spiral of decline continues, and the tree becomes stressed, sometimes with minimal to no indication above ground early on. Then insects and disease can move in, worsening the problem.

Girdling tree roots

If the mulch is installed too thickly – more than 2 to 3 inches – at the time of planting or within the first few years, our issues can become bigger. The tree was transported to the site for planting and was either in a container or balled & burlapped (B&B), but those original roots are nothing compared to what they can become. In comes problem #2, girdling roots. As roots continue to grow, and depending on soil conditions, feeder roots will struggle to penetrate compact soil. Depending on soil compaction, they may only be able to navigate the hole in which the tree was placed.

Next, add the issue of excess mulch while those roots are searching for their needs. They may continue to grow in circles through the hole and then into the mulch, searching for the water, oxygen and nutrients they need and strangling the tree in the process.

Can you imagine? Our responsibility is to enhance the environment to encourage optimal tree health. In my opinion, we need to discuss this issue more, and not just in the tree care industry but within the entire green industry.


My goodness, I could I go on and on about this topic, but let’s talk about solutions. How do we solve this problem?

For starters, when we do estimates for our consumers, let’s educate the public about common issues that don’t always involve a pesticide solution. What does this conversation look like? We arrive on a property and see volcano mulching, (Photo 1). Well, we all know we can’t diagnose any situation without evaluating the entire tree, but doesn’t this picture start to give you an idea of what the canopy looks like? Unfortunately, there are many times when our best solution is to remove a tree like this and start fresh, including creating a better environment for the new tree’s success.

Photo 1: We all know we can’t diagnose any situation without evaluating the entire tree, but doesn’t this picture start to give you an idea of what the canopy looks like? All photos courtesy of the author.

A good environment

Our next estimate is the tree in Photo 2. The homeowner has explained that it was planted in memory of a deceased family member. Now we must explain, in a non-offensive manner, that this tree has little chance of complete success. Why? This poor tree, like many, has been planted too deeply and in a turfgrass area.

When trees are planted in the middle of a maintained turfgrass area, there’s a chance it has experienced mechanical damage either from a lawn mower or a string trimmer. If it’s a maintained lawn with an annual program, think about the products being applied where the roots of the tree must grow. Our conversation should involve education, but also the recommendation of a mulch bed to enable this tree to live up to its potential.

Photo 2: This tree has little chance of complete success, because it has been planted too deeply and in a turfgrass area.

Construction damage

Common construction issues can be seen in Photo 3. A new development is being built, and the contractors are required to “keep” some trees. They move, remove and/or replace topsoil. Many times, the trees they are required to keep get buried deeper. Also, the soil around the tree can become incredibly compact, leaving no beneficial foundation for the tree. What was the point? This tree likely will not survive. The idea was to retain a mature tree, but that tree is now going to begin to decline.

Photo 3: Common construction issues can include removing and/or replacing topsoil, with trees getting buried deeper or the soil around the tree becoming incredibly compact, leaving no beneficial foundation for the tree.

An estimate was requested for the tree in Photo 4, because the tree wasn’t looking healthy and the homeowner wanted to save it. Upon inspection, a professional arborist would evaluate and ask multiple questions. The number-one question was, “When did the new patio installation take place, and did it correlate with noticing a problem?” The second might be, “Was this tree at ground level before the construction?”

Construction equipment is incredibly heavy and can compact the soil so tremendously that the 50% pore space needed in soil composition is reduced significantly, if not completely.

Photo 4: This tree wasn’t looking healthy and the homeowner wanted to save it. The first question was, “When did the new patio installation take place, and did it correlate with noticing a problem?”

Gather information on the tree

How do we discuss solutions for all these examples?

First, we need to ask questions. Here are some I recommend:

  • What species of tree is it? (Some species have more prolific root growth than others, and this matters)
  • Does the canopy look full? Many times, a good rule is, if decline is 30% or less, our success rate is higher.
  • Is the root collar exposed? The root collar is an incredibly valuable and vulnerable portion of the tree. If it is not exposed, chances of disease and rot are more likely to occur.
  • Can you visibly see girdling roots?
  • Is there excess mulch? If so, did you try to move some by hand to evaluate depth?
  • What other signs and symptoms can you see?
  • What is the site history?
  • Was construction performed recently or even in years past? Did you know that several initial stressors may not show for several years?
  • Is the soil compacted?
  • Is the area too wet?

Root-collar excavation

Root-collar excavation is a non-intrusive and pesticide-free solution that can create amazing results if performed early enough in this devastating decline pattern. Using compressed air and the right excavation tool, we can offer an exploratory solution to better determine our recommended course of action. Root-collar excavation involves removing soil or organic matter from around the base of a tree. The air-excavation tool is connected to a hose attached to an air compressor, preferably able to provide 185 cfm (cubic feet per minute) of air pressure. This can produce an excavation rate of 1 to 1.5 cubic feet of soil per minute.

Watch out and plan properly though, because the soil/dirt is blown everywhere. Be sure to wear appropriate personal protective equipment (PPE) and plan accordingly. If the tree is planted too deeply, there’s a possibility that some soil will need to be removed from the site. You may want to add an organic soil amendment to available soil to complete the job. These factors must be considered prior to starting the job. When bidding this job, ensure you allow for time needed to prep, perform and perfect when complete. This alone can take much longer than excavating.

Root pruning

The time has come to perform the job, and I assure you that this process draws attention, so planning this process can be beneficial in addressing neighbors and lots of their questions. In Photo 5, we initiated the excavation and cleared the soil, and now we need to evaluate again.

Root pruning, in my opinion, is an incredibly difficult process when you need to consider what and how much to remove. A great rule is never to prune more than 25-30% at any one time. This rule applies above ground, too, and for so many plants. When we prune tree branches, that’s the rule. When we mow our lawns, that’s the recommended rule, and it’s the recommended rule below ground, too.

Be sure all tools to be used for pruning are sharp and clean! Be sure not to damage any other part of the tree. Care should be taken for any roots greater than 1 or 2 inches, as their function may be for stability or anchoring the entire tree. Do not remove everything that looks like a problem to you all at once, or I can assure you that you could effectively create more problems for the tree you were hired to help with.

Photo 5: Root pruning is a difficult process when you need to consider what and how much to remove.

Soil amendments

Next, we evaluate the dirt and make it soil. If you need to add amendments, this is a great time to do so. Most important is to keep all exposed roots hydrated. Fine roots can dehydrate very quickly, and when they do, they die. Be sure to have a water source nearby to manage this during the process.


In discussing this with professionals, I have learned the best conversation involves a lot of detail and to keep your consumer involved in the process. Be sure to set expectations! This is critical in any recommended solution in our business, but incredibly important with this recommendation. We don’t have X-ray vision and cannot see the soil beneath the surface.

Be honest and open with the consumer, and remember, the best plant-health-care (PHC) businesses want to be the preferred “property concierge.” I want my customers to call me with any concern, even if it’s not a service I can provide. I’ve made a point of creating a network of amazing people (I feel they are amazing) who can help. Use your resources. We are tree people, and our passion in this area impacts more than just our customers, so create alliances and work with people with whom you feel you can learn. Build your foundation along with those of the trees!

Finally, below are some reference materials for more reading and learning. Here’s to building your and the trees’ strong foundations!

Additional resources

Excess Mulch

Excess Mulch Problems | University of Maryland Extension (umd.edu)


FS099: Problems With Over-Mulching Trees and Shrubs (Rutgers NJAES)


Mulch Volcanoes – A Harmful Practice for Trees | Nebraska Extension (unl.edu)

Planting Is Too Deep

(PDF) Effects of Planting Depth on Landscape Tree Survival and Girdling Root Formation (researchgate.net)

Girdling Roots and/or Objects (See below)

Compact Soil

Protect tree roots from soil compaction (MSU Extension)



What effects will construction activities have on nearby trees? | Horticulture and Home Pest News (iastate.edu)

Kathy Glassey is director of renewable resources for Monster Tree Service, a 12-year TCIA member company based in Fort Washington, Pennsylvania. This article was based on her presentation on the same subject during TCI EXPO ’22 in Charlotte, North Carolina. To listen to an audio recording created for that presentation, go to this page in the digital version of this issue of TCI Magazine online at tcimag.tcia.org and, under the Resources tab, click Audio. Or, under the Current Issue tab, click View Digimag, then go to this page and click here.

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