How to Kill Tree Roots
Cut small problem roots., Dig a trench to block roots., Kill suckers with herbicide., Replace damaged pavement with crushed stone or mulch.
Step-by-Step Guide
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Step 1: Cut small problem roots.
Although labor-intensive, this directly addresses the issue with no risk to nearby plants.
Dig out the soil around and under the root first, then cut with a root saw or loppers.Cutting roots aggressively can put the tree in a long decline, potentially killing it over many years.Follow these rules of thumb to prevent this:
Multiply the diameter of the tree by eight.
That's the minimum distance from the trunk you can cut with low risk of serious harm.Cut roots on one side of the tree only, especially if you're risking a cut closer than the minimum distance. -
Step 2: Dig a trench to block roots.
Cutting roots once is only a temporary solution.
To maintain the area, you may need to dig a trench and cut away the roots annually — or up to twice a year for aggressive root systems.You can save yourself from this chore if you dig one deep trench (ideally through the entire topsoil), then install one of these barriers before backfilling:
Galvanized metal roofing.
Fold the top over to avoid a dangerous sharp edge.A double layer of HDPE plastic, Overlap sections of barrier by at least 12" (30 cm) so roots can't slip through. sometimes available free from feed storesFor best results, buy a commercial root barrier treated with herbicide.
Trifluralin is a common option unlikely to harm nearby plants., Some trees respond to cut roots or other damage by sending up new suckers from the root system.
To kill these selectively, sever the root so the herbicide does not travel to the main tree.
Apply an herbicide that contains glyphosate or triclopyr amine carefully to the sucker so it does not spray to nearby plants.Many suckering plants grow aggressively.
If you are not willing to kill the main tree, you will need to repeat this treatment or periodically dig up the suckers by hand.
If you've cut down the main tree but suckers are still appearing in your yard, your only option may be to apply a broadleaf herbicide.
This will kill all vegetation in the area.
Repeat each time suckers appear until the roots run out of nutrients., It may not be possible to kill large surface roots without killing the whole tree.
If that's not an option, you can install a surface the tree cannot break through.
Since this does not kill the roots, it will not protect garden areas or sewage pipes.
Carefully remove any damaged concrete with minimal damage to roots.
Cover the area with geotextile fabric.
Leave 6" (15 cm) of clear ground around the trunk, or 12" (30 cm) for large trees.Cover with 3–4" (7.5–10 cm) of crusher run (a type of crushed stone aggregate) or 6–8" (15–20 cm) of coarse mulch.
Mulch is less effective, and may wash away in rain.
Edge the material with stones to minimize shifting. -
Step 3: Kill suckers with herbicide.
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Step 4: Replace damaged pavement with crushed stone or mulch.
Detailed Guide
Although labor-intensive, this directly addresses the issue with no risk to nearby plants.
Dig out the soil around and under the root first, then cut with a root saw or loppers.Cutting roots aggressively can put the tree in a long decline, potentially killing it over many years.Follow these rules of thumb to prevent this:
Multiply the diameter of the tree by eight.
That's the minimum distance from the trunk you can cut with low risk of serious harm.Cut roots on one side of the tree only, especially if you're risking a cut closer than the minimum distance.
Cutting roots once is only a temporary solution.
To maintain the area, you may need to dig a trench and cut away the roots annually — or up to twice a year for aggressive root systems.You can save yourself from this chore if you dig one deep trench (ideally through the entire topsoil), then install one of these barriers before backfilling:
Galvanized metal roofing.
Fold the top over to avoid a dangerous sharp edge.A double layer of HDPE plastic, Overlap sections of barrier by at least 12" (30 cm) so roots can't slip through. sometimes available free from feed storesFor best results, buy a commercial root barrier treated with herbicide.
Trifluralin is a common option unlikely to harm nearby plants., Some trees respond to cut roots or other damage by sending up new suckers from the root system.
To kill these selectively, sever the root so the herbicide does not travel to the main tree.
Apply an herbicide that contains glyphosate or triclopyr amine carefully to the sucker so it does not spray to nearby plants.Many suckering plants grow aggressively.
If you are not willing to kill the main tree, you will need to repeat this treatment or periodically dig up the suckers by hand.
If you've cut down the main tree but suckers are still appearing in your yard, your only option may be to apply a broadleaf herbicide.
This will kill all vegetation in the area.
Repeat each time suckers appear until the roots run out of nutrients., It may not be possible to kill large surface roots without killing the whole tree.
If that's not an option, you can install a surface the tree cannot break through.
Since this does not kill the roots, it will not protect garden areas or sewage pipes.
Carefully remove any damaged concrete with minimal damage to roots.
Cover the area with geotextile fabric.
Leave 6" (15 cm) of clear ground around the trunk, or 12" (30 cm) for large trees.Cover with 3–4" (7.5–10 cm) of crusher run (a type of crushed stone aggregate) or 6–8" (15–20 cm) of coarse mulch.
Mulch is less effective, and may wash away in rain.
Edge the material with stones to minimize shifting.
About the Author
Patricia Torres
Experienced content creator specializing in lifestyle guides and tutorials.
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