A Guide to Digging Up Tree Roots

Unless you’re a professionally trained specialist, or you know someone who is, you probably don’t know the minutiae of digging up tree roots. Tree roots can be tough, making it hard to dig them up or remove them entirely, and even after you remove them, you might find out you damaged the tree.

This guide will help you understand:

• Why you might remove tree roots
• Vocabulary important to the understanding of removing roots
• Trees that are more prone and less prone to growing exposed roots

Reasons to Remove Tree Roots

Generally speaking, it’s best to leave tree roots alone. When you remove a tree root, you run the risk of irreparably harming the tree, which results in the total loss of the tree. That being said, there are a few reasons you might want to remove tree roots:

• If they are in the path of a walkway and present a hazard to anyone (but especially elderly people)
• If they harm the integrity of nearby structures, i.e. your house or sewer system
• If they inhibit the aesthetic of your yard to the point you can’t sell your house

If your only issue with tree roots is that they get in the way of your gardening or that they aren’t pretty, it’s probably better to just remove the tree entirely. Just because roots are exposed doesn’t mean you should remove them. Some of them are vital to the tree’s survival.

Call before you dig

It’s more than just a phrase. It’s light and pithy and easy to remember, and that’s the point. You need to call 811 at least three business days before you intend to start your project. The appropriate utility companies will send out people to mark where the various gas, electricity, and water lines are. Not calling before you dig is irresponsible and can harm you and others.

Don’t be that person who cuts out the electricity on a hot summer’s day or causes a gas leak or watermain break. No one likes those people. Regardless of whether you’re digging up roots, planting a tree, or building a deck, call if your project involves digging.

Tree Words

If you decide that the need to remove trees is legitimate, there are a few terms you should be familiar with before you start.

The critical root radius (CRR) is a figure used to determine a protected root zone based on the diameter (in inches) of a tree at four-and-a-half feet high. That number multiplied by one or one and a half feet will give you the CRR. Multiply the CRR by two, and that will give you the protected root zone (PRZ). This equation is primarily used for narrow-growing trees.

The dripline is the perimeter created by water falling from a tree’s widest layer of leaves (usually the bottom layer); some guides recommend that no roots inside the dripline be cut or dug up. The dripline also defines the critical root zone (CRZ) or protected root zone (PRZ).

Feeder roots are the roots most likely to become exposed. They are close to the surface, and as they grow, they break the ground. These roots are responsible for absorbing water and nutrients.

Pneumatic digging is a method of trenching that uses air to dig without damaging vital roots.

The protected root zone (PRZ) is the area around the tree in which no roots should be cut. You should also treat the roots outside the PRZ with care, but those inside are particularly vulnerable.

Structural roots provide the foundation for the tree. If you compromise these roots, the tree will lean and you will need to take it down.

Trenching is the process of digging around roots to be able to remove them. It often damages or severs roots unless executed via pneumatic digging.

Cutting Tree Roots

The most complex—and most important—part of cutting tree roots is determining the PRZ, but it’s not the first step. Here’s a basic breakdown of the process:

1. Thoroughly evaluate whether or not you need to cut the tree roots. Purely aesthetic reasons are not really justifiable.
2. Call 811 at least 3 business days before your project so company representatives can mark utility lines. Depending on state regulations, avoid digging within 18 to 24 inches of utility lines.
3. Define the protected root zone by either the equation CRR (tree diameter in inches at 4.5 feet times 1.5 feet) times two. Do not cut inside the PRZ.
4. Remove the soil around the tree root you want to cut. Remember to avoid getting too close to power lines.
5. Mark the line where you will cut the tree. This prevents cutting the heart of structural and feeder roots, and allows for more precise work.
6. Cut the root with a saw.
7. Fill in the hole with dirt or organic mulch.
8. Monitor the tree closely for signs of leaning, illness, or decay.

Alternately, you can reduce this to a three-step process:

1. Repeat Step 1 above (Do you really need to cut some roots?)
2. Repeat Step 2 above (If yes to Step 1, Call 811 to get utility lines marked.)
3. Call a professional tree services company. They know what they’re doing, and they are much less likely to harm the tree.

Get to the Root of the Problem

See what I did there? On a serious note, deciding whether or not to cut tree roots comes down to one yes-or-no question: Does the tree root have the potential to cause harm to any person or structure?

If the tree root in question does pose a serious problem, get some professional advice. They may say you need to go ahead and take the tree down, or they might be able to fix your problem quickly.

If your problem with a root is non-life threatening (i.e. it isn’t going to fall on your house, disrupt your pipes, or cause someone to break an ankle), leave the tree alone. Chances are you will do more damage than good, and who wants to spend the money on removing what was a perfectly healthy, innocent tree?

At the end of the day, trees are an important part of our ecosystem, and they serve decorative and useful purposes in our yards. Don’t cut tree roots unless it’s absolutely necessary.