Root Flare Exposure and Tree Health

Root flare exposure is critical to a tree’s health. However, all too often, trees are planted too deeply. Nearly eighty percent of trees in urban areas have had their root flares covered by dirt during planting. Others have had their root flares covered up by mulch. A tree that does not have its root flare exposed is set up to have health problems.

What is a Root Flare?

‘The root flare is the portion of the tree where the trunk transitions into the root system’ (Tyler Moore). Unlike the roots of a tree, the root flare has bark. The main function of bark is to protect. Bark protects the living tissue, known as the cambium, from damage. It acts like a shield, keeping disease and pests from its critical parts.

Bark is aerial tissue and is intended to be exposed to air. Covering the tissue for long periods of time, with either dirt or mulch or water, can cause rot or the development of adventitious roots that can crowd and girdle the root flare. Adventitious roots are roots that develop in places that shouldn’t, under normal circumstances.

A good analogy for this is when we submerge our skin in water too long. The skin, which is designed to be exposed to air, not constantly submerged in water, becomes wrinkled and susceptible to nicks. Similarly, when a root flare is covered with dirt or mulch or excess water, the bark breaks down and can rot away. A tree’s root flare needs to be exposed to oxygen in order to thrive.

Function of the Root Flare

The root flare is the intersection of the root system and trunk of the tree. It is the main center of exchange in materials within the tree. This intersection is made up of living tissue that is responsible for transporting nutrients and water, gathered by the roots, to the rest of the tree. Likewise, sugars created by the leaves are transported through down to the roots via the root flare. In other words, if the root flare is damaged and cannot effectively transport needed nutrients to the canopy, it will show in the leaves or branches of the tree.

Signs and Symptoms of Root Flare Damage

The most prevalent sign of root flare damage is loss of leaves or branches. You might notice that your tree is not producing as many leaves in the growth season as it has before, or that the tree has more dead branches than usual. Another sign would be if the canopy is affected in sections. For example, half or part of the canopy appears stressed, but the rest of the canopy appears fine.

Disease, insect infestation, and dieback are other possible signs of root flare damage. If a tree’s root flares are not exposed, it is more susceptible to secondary stressors.

How to Uncover a Root Flare

Begin removing the dirt slowly using a shovel or hand shovel, being careful not to nick the bark. Pay great attention to the slope of the trunk where it enters the soil. You want to expose the area of the trunk where it begins to taper and the main anchoring roots of the tree are visible.

If you don’t have the time or the tools, it might be best to hire a certified arborist to do the job. A certified arborist will utilize the right tools and take the care needed to ensure that your tree’s root flare is not damaged in the exposure process. Ask if the arborist company uses an AirSpade and is properly trained in its use. An AirSpade removes dirt around the root flare with a pressured air nozzle, specially made for work around tree roots. 

Once the root flare is properly uncovered, it is important to remove any girdling roots. As Tyler Moore, put it, “Root flare exposure is like exploratory surgery. You don’t know what you have until you get there.”

Determining which girdling roots or other smaller roots to remove is not within the scope of this article. It is best to consult with a certified arborist before removing or cutting any part of your tree, especially the roots.

Once you have uncovered the root flare and removed any unwanted roots, it’s important to finish off the area. Placing bricks or forming some type of embankment, (if necessary, to keep dirt from building up again over the root flare is helpful.

Exposing root flares should be a one-time job. Rain and weather can cause dirt to build up again over the root flare if a proper retaining wall has not been put in place to prevent erosion. Planting flowers or other plants near the root flare can lead to build up. Monitor root flares in your yard. Your trees will be more adept at fighting off disease, insects and drought.

Live in Denton County, Texas? Contact Tree Shepherds. Our ISA certified arborists can help you with all of your tree care needs.

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Krista White
Krista is a member of the marketing and education team at Tree Shepherds. A lifelong learner, she loves writing about anything from Hemingway to Quercus macrocarpa.