I've got two trees with exposed roots. Ivy had been covering the roots but after a drought last summer, it's all dead. Now I've got a large bare spot (15Âx30Â) with some seriously exposed roots (up to 12" above ground). I was thinking of putting in a retaining wall around the trees and filling it in with dirt up to their trunks. I don't want to upset them if they're ok though. Any advice is greatly appreciated. I was just going to use the oldcastle grey precast stones like they sell in lowes and home depot, any thoughts?