Lining a raised bed to prevent tree roots
This is my first time posting on the tree forum as I am normally in the greenhouse or kitchen forums. But I have a common problem, which is tree roots occupying the raised beds in the kitchen garden. My plan is to excavate the raised beds and put a liner of sorts at the bottom of the bed. I understand that this may only be a temporary fix and that tree roots are clever and aggressive. Given that, what sort of liner do you recommend? Any other words of wisdom?
The raised beds are about 15' from the trees and the trees are an aspen and a golden willow. The trees are 14 years old and this just became a problem last year. I know these are thirsty trees but we love them nonetheless and they are a definite asset in our landscape. The afternoon shade they provide is actually a good thing for the veggie beds, so can get a little reprieve from the heat.
Thanks for whatever wisdom you can share!