Root Flare Excavation For Trees

Apr 11, 2015

The average person has probably only heard of the basic landscaping methods of caring for trees, such as pruning or fertilizing. In some cases, however, root flare excavation can be just as important, if not more so than these actions. Whether or not you are familiar with it, being aware can make the difference between having healthy trees on your property and have poorly nourished ones which are dying.

What Is The Root Flare?

Before getting into root flare excavation, you need to understand what the term root flare refers to . This is the bottom area of the tree, typically right above the ground, that flares out1. It is this part of the tree where root tissue becomes stem tissue and the bark is formed. While root tissue is known as rhizomonas, root flares are different. In fact, root flare should be in contact with the atmosphere to function properly.

Why Should The Root Flare Be Exposed?

For a tree’s root flare to work and grow as it should, it needs to be exposed so it can come in contact with the atmosphere. This means that you should never cover it with mulch, fills, or soil as it restricts the tree’s access to the air. This weakens the tree in general and also makes it more susceptible to additional stresses such as insect infestations or disease. Part of the issue is that the trunk of the tree needs to be able to breathe properly and when it can’t, the bark will stay moist, which should not be the case2. As such, the tree may develop poor shoot elongation, defoliation, branch die back, or diminished yields.

Essentially, anytime the root flare is covered, whether by soil, mulch, or something else, it hides the roots, making it impossible to tell if they are girdling or circling. In either case, these roots will “choke” the tree, slowing down growth significantly. It is actually sometimes even more likely for trees with buried root flares to experience the issue as the roots will do whatever they can to reach the water and nutrients they need for growth3. This can become an issue whether the root flare is covered because of planting the tree too deeply, confining it within a planter or container which is too small, or is covered with mulch to prevent weeds.

You may be wondering why the root flare or root collar of your trees needs to be exposed when not all of those in the natural world, such as in forests, are4. Keep in mind that the trees on your property are exposed to more water than those in the forest, thanks to people’s tendency to over-water their plants. This leads to an increase in moisture along the root flare, increasing the risk of decay. In addition, if you asked an arborist to evaluate the trees with buried root collars in the forest, they would most likely say that those trees are not as healthy and will not grow as well. Even comparing trees in the forest with buried root flares with those who have the flare exposed will show you a significant difference in health.

How To Tell If Your Tree Needs Air Spading

The best way to tell if your tree needs root flare excavation is to have an expert come and take a look. You can do a simple visual test yourself to get an idea, and then hire an arborist if you are still unsure. If the entire area of your tree that sits above the ground is straight, resembling a telephone pole, then the tree flare is underground and needs to be excavated. If, however, the tree is straight until a few inches to feet above the ground, at which point it starts flaring out so the widest part is in contact with the grass or soil, it should not need to be excavated.

To prevent any issues with the root flare, take extra care when planting or transplanting any trees. Have an arborist do the job for you if you aren’t confident. Otherwise, ensure that you don’t dig the hole too deep. Remember that young trees are more likely to die because of being planted too deeply than other issues.

Is DIY Root Crown Excavation Possible?

Technically, it is possible to do a root flare excavation yourself, but most arborists would not recommend it. You may think that you will save money by doing this job yourself, but you can easily injure or kill the tree. That is because root excavation is a very delicate process; the roots of the tree are essential for providing it with nutrients. This is more challenging because the bark underneath the ground will be moist, making it even more fragile.

If you do attempt to do a root collar excavation yourself, be sure to wear gloves and rely on hand tools instead of electric ones. Don’t use water unless it is in a very soft and flowing stream as any stronger blasts may cause severe damage to the soft, fragile bark found at the tree’s base.

Uncovering The Root Collar

During root excavation, an arborist will work carefully to remove the soil covering the tree’s root collar. They will also remove any other objects, such as wires, that get in the way of the roots and root flare. The arborist will work either alone or with a team of experts to expose the root collar. Then, they will remove the small roots that are trying to grow up and reach the air, leaving the depression from the exposure open. This open area will gradually fill in as the flare keeps expanding as the tree gets healthier. The arborist may add shredded cedar mulch in a thin layer on top of this depression, but they will not add more than this.

The majority of arborists will use a tool called the air spade to excavate the root flare. This tool is similar to a sandblaster, but without the sand and it blows air at high velocities. This process allows it to remove the soil while preventing damage to the tree itself, including the smallest roots.