Introducing a border around established trees/shrubs
Back again for a bit more advice. . .
I have a lot of established trees and shrubs at the back of my garden with no discernible border. Initially there were a lot of weeds in between which I have largely removed. I was keen to introduce so sort of formal border which I have largely marked out after removing the weeds but there a lot of superficial roots extending to under the "lawn" (mainly composed of ground ivy/creeping charlie at the minute).
I am hitting roots when I try to dig more than about 2 inches to create the border and I am worried about damaging the roots.
Any ideas how I should proceed? (if at all)