The existing planter was formed of Trex brand composite wood decking material with a redwood top. The Trex was weathering very poorly. (so much for this material lasting longer than wood!) Maybe it was a bad batch, but the surface was crumbling and breaking down to about 1/3rd of its depth. The bad material was peeled off and then the entire wall was covered with expanded metal lathe (the redwood top replaced with a metal stud). Cap was filled and entire unit scratch coated. Stone depth was limted by the overhang of the cap so no dramatic relief could be obtained beyond say 1.5 - 2 inches at the top. Some build out of larger stones near the base was acheived.