Tree root barriers

Question: I have a large linden tree about 15 feet away from my vegetable garden which never caused any issues, but now I am finding a few of my raised beds full of roots from the tree.  I am considering installing a poly root barrier just outside of the garden to keep the roots at bay.  This would involve cutting no more than 20% of the tree roots on one side.  How safe will that be for the tree and will the severed roots that remain under some of the raised beds continue to grow once they are no longer connected to the tree? Cutting the tree down or moving my garden are not options I can consider.

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied June 26, 2023, 7:24 AM EDT
response: The poly-landscape barrier idea is a good one.   I suggest you consider digging the trench up to 18” deep for the poly though— these roots are very “assertive” and can easily get under a 12” barrier.  If you continue to have problems, you could also use a long spade (there is one called “root slayer” I would recommend) and simply root prune them each spring.

responder: The Question Asker Replied June 26, 2023, 8:08 AM EDT
response: Thank you for your prompt response.  I was planning to install a 36” deep barrier so that I don’t have to worry about any assertive roots, but the deeper you go, the more expensive they are.  Is 36” deeper than I will need?Sent from my iPadOn Jun 26, 2023, at 7:24 AM, Ask Extension <<personal data hidden>> wrote:

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied June 26, 2023, 11:19 AM EDT
response: My feeling is yes.  In the case of deeply rooted trees such as Oak, that may be of help.  But most of this trees roots will be in the upper 12-18 " of soil.  At one time you could purchase landscape fabric that was bonded with an herbicide that would deter roots that come into contact with it.  I checked on line before I answered but did not see that product in existence any more.

responder: The Question Asker Replied June 26, 2023, 5:01 PM EDT
response: Thanks for that answer.  You’re the only one who’s given me the approximate root depth of a linden.  I think I can feel confident with a 24” deep panel which is a little more cost effective.   Just an FYI, in case someone else has a  similar problem.....I’ve been doing quite a bit of reading on the subject since discovering the roots in my veg garden, and the herbicidal barriers are still available here  https://www.treestuff.com/biobarrier/. I try to be as organic as I can with my vegetables, so have opted against an herbicide barrier in soil only a few feet away.You’ve been extremely helpful and I sure appreciate it!Sent from my iPadOn Jun 26, 2023, at 11:19 AM, Ask Extension <<personal data hidden>> wrote:0107116

responder: Thank you for your question! Rebecca Finneran Michigan State University Extension Senior Horticulture Educator Learn how t be a Smart Gardener here www.migarden.msu.edu Replied June 27, 2023, 10:41 AM EDT
response: Good tip.  Thanks.  And thank you for the nice feedback.  We answer upwards of 8,000 questions a year and love to share that with others.