How to Kill Oak Roots But Not Trees​: 6 Tips for Dealing With Oak Tree Roots

While oak trees are magnificent, their wayward roots can cause issues when they encroach on other areas of your landscape, hardscape, or even your home’s foundation. Whether they’re lifting sidewalks or interfering with your landscaping, you might need to learn how to kill oak roots but not trees. The good news is, in many cases, it’s possible. Here are six ways to address aggressive oak roots without damaging the tree itself.

1. Consult a Professional Arborist

If you’re set on saving your oak tree, your best strategy is hiring a professional arborist. A key part of the job of an arborist is performing tree surgery to remove problem roots without killing the tree. They can provide a definitive answer as to whether or not you should cut the tree down, avoiding any unnecessary efforts if the tree can’t be saved.

2. Prune the Roots

If you’re wondering whether cutting tree roots will kill a tree, you can often safely cut a few of an oak tree’s lateral roots without harming the tree. Oaks mainly depend on their deep taproots for stability, while the lateral roots are responsible for gathering nutrients. However, it’s best to only cut roots that are no thicker than three inches in diameter, and avoid trimming too close to the trunk. If you decide to go the pruning route, use a clean, sharp saw or pruning tool to make precise cuts to give the tree the best chance to heal from the wound.

It’s important to note that, aside from pruning key taproots, removing too many roots at once can weaken or even kill the tree. It can also cause dangerous structural damage, making the tree more likely to fall, especially during extreme storms or high winds. If you’re still unsure how to proceed, contact a certified arborist for a consultation.

3. Dig a Trench

Digging a trench can effectively buffer oak tree roots to prevent them from growing any further. The ideal depth will depend on how deep the tree roots grow, and for oak tree roots, the majority are within the first one foot of soil depth (although they can extend to a depth of up to four feet).

To determine a safe digging distance, measure the tree’s circumference at your chest height, then divide that number by 3.14 to find the diameter. Then, multiply the diameter by five to get the minimum distance in feet to avoid cutting critical structural roots. For example, if your tree has a three-foot diameter, keep digging activity at least 15 feet away in all directions.

4. Install a Root Barrier

Installing a root barrier can help control problem root growth without harming your tree. You can place these specialized barriers in the soil to redirect roots away from areas where they might cause issues. Always install barriers at least one foot deep to effectively block the oak tree roots.

5. Remove the Tree

Unfortunately, an oak tree with problem roots can’t always be saved if it's posing a hazard to your home, or if it’s becoming too much of a hassle to keep up with. Tree roots can grow back if you cut them, and they can even grow if the tree is dormant. While it’s a tough decision, sometimes cutting the oak tree down is the best solution. Contact a local stump removal service and be sure to specify stump removal in your contract to make sure the roots can’t continue to grow.