I am not a gardener so after low maintenance plants that I could put in a long raised bed along our back fence. I just want something that breaks up the expanse of fence, was thinking bay trees and lavender? Would I be able to cover the soil in the beds with large shingle or cobbles to try and avoid dog digging in there!? Also any idea how much it would cost a gardener to build the beds? It’s approx 6m long the fence. Thanks :)