I have a very large, 6 foot diameter and 12" high, relatively fresh fir stump in my tiny front yard. My plan is to 'wrap' this stump with a metal roofing planter that is 24" high. My question for this forum is should I back fill with a potting soil or regular garden dirt? The stump surface is solid at this point and drainage would be taking place around the edges of the stump like a regular pot until the stump starts to rot. I plan to plant a vine maple in there which has a similar environment in nature and also perennials that will spill over the edge. Any opinions will be appreciated.