My neighbor has a line of tall arborvitaes next to my vegetable garden and I'm getting invaded by the roots. I think I need to install a root barrier. The products I see are generally reprocessed polypropylene type 5 plastic for the hard ones, and high density polyethylene (HDPE) type 2 plastic for the more flexible rolls. Fabric barriers won't hold up. Are these plastics bad for use in organic gardens? Any ideas for a safer barrier? I was thinking maybe metal roofing, but they're probably treated with chemicals and I question using metals. Seems like there are no good options short of cutting the damn things down in the middle of the night :) Thanks

1 Answer 1


I use aluminum flashing as a root barrier between my yard and my neighbors' yards, installed directly under my fence. This can have sharp edges, which is why it's under the fence. Works great, except when something tries to climb over the top.

As far as I know, there are no chemical treatments on the aluminum (I've never seen residue of any kind or noticed any smell whatsoever). It comes in 50 or 100 foot rolls, with widths up to 14 inches (I tend to like the 8" width) and is relatively inexpensive.

For installation, I would actually back the flashing with bricks or concrete pavers on the side towards the arb, This serves two purposes - to protect the flashing from being crushed by foot traffic/lawn movers and to prevent you from cutting your hands on any exposed edges. You install the pavers after the flashing. You'll also need some of the same spikes that roofers use to install rain gutters (1 spike for every three feet of flashing "run").

  1. Use a flat spade to cut a V-trench
  2. Install the flashing about 1/4-1/2" below the top of the soil.
  3. After you've finishing installing the flashing, hammer the spikes into the flashing at a parallel to the soil surface. You need the spikes to secure the flashing in place and prevent frost-heave (maybe every 3 feet or so).
  4. Backfill the trench and tamp down the soil next to the flashing.
  5. After a couple of days (and a good rain or watering to settle the soil), install the pavers by digging a shallow, flat trench up against the flashing and dropping them into place. I'd keep them a little higher than soil level, but that's up to your own preference.

You now have a solution that should last just about forever.

  • Thanks. Sounds like a good solution, I'll give that a try. One question though about the spikes. I think you mean hammer them through the flashing parallel to the surface. 90 degrees would be perpendicular, vertical/up-down to the soil surface.
    – Bluez6
    Apr 13, 2020 at 0:17
  • Yeah, you're right about the spikes; and to think that I used to be good at geometry. I've edited the post accordingly. If this works for you, please upvote and accept the answer so that the question is catalogued properly on the site. If it doesn't, please let me know via a comment. Thanks!
    – Jurp
    Apr 13, 2020 at 3:26
  • I dug a trench around the inside of my garden and installed 14" aluminum roll flashing as advised. Digging an even trench was really tough as the soil is very rocky here in the northeast. I came across a rock too big to dig out, but it was pretty easy to cut out the shape of the rock from the bottom of the flashing. I ended up using long gutter screws rather than spikes and it worked really well. I was surprised just how well the screws grabbed in the dirt and pulled in the flashing. Worked great.
    – Bluez6
    Jun 16, 2020 at 2:37
  • I think this should be a great solution. I had some really deep roots, but the 14 inch flashing should hold back the great majority of them. I won't know until next year when I till the soil again in the spring, but I confident this will work.
    – Bluez6
    Jun 16, 2020 at 2:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.