If you have trees growing near your home or utility lines, at some point you'll have to cut roots in order to control the tree's root growth. Roots from mature trees can disrupt driveways, septic systems, walls and other structures if planted too close. Knowing when and how to cut roots can mean the difference between healthy pruning and killing your tree. Cutting just one large root can destroy up to 1/4 of the tree's root system, so be careful when you cut. Once you cut a large root, if the tree survives, it will respond to the loss by producing lots of additional root offshoots, making future cuttings an unnecessary task.
When To Cut Your Tree Roots
If you have to cut your roots, do it in June or July.
Step 1-Measure A Safe Cutting Distance
Depending on the soil conditions and the tree, tree roots can extend out three times the distance the tree is tall. So, a 60-foot tree may have a 120-180 foot long root system. The closer to the tree you get, the larger the root and the more likely the tree is to be harmed or killed by cutting. As a general rule, the distance for any root to be cut from a tree’s trunk is 18-inches for every 30 inches of trunk diameter, measured at 4-to-5-foot height. So if your tree's diameter is 5-feet, you should cut the root no closer than 3-feet from the trunk of the tree.
Step 2-Find The Root
Chances are if you know you have a root problem, there's evidence-a cracked sidewalk or drive, a buckled wall etc. So, you have the general area of the root, now you need to find it. Dig. Most roots are only 4-to-8-inches below the surface. You'll be able to find the root by hand digging a trench perpendicular to the area where the root damage is.
Step 3-Cut The Root
Once you've exposed the root, cut it cleanly using a bow or other saw. Do not hack at the root or leave a ragged edge. Not only will it traumatize the tree, the tree will respond to hacking and a ragged root by sending out more root shoots than with a clean cut. Apply a protective coating to the cut to protect the root from insects, pests and disease.
Step 4-Finish Up
Once you've cut the root you'll need to take additional steps to ensure it survives. Plan on watering the tree at more regular intervals and on pruning heavy branches over the next year or two to compensate for extensive root removal, particularly if you have removed a flare root.
Tips For Cutting Roots
- Make clean cuts with a saw. Don't hack at the root with a shovel. Don't leave a ragged edge.
- Never cut more than one flare root per tree.
- Cut as far away from the tree trunk as you can to resolve the root issue.
- Install a copper impregnated root barrier around or in front of the root after cutting it to prevent future root problems.
- If you have trees near sewer and water lines, apply commercial products like "Root-X" before the roots become large enough to split your pipes. Application is easy, doesn't harm the tree like cutting a large root would, and is less expensive than replacing new utility pipes.