I'll be planting bamboo, and need a barrier in the soil to keep the roots from spreading. Any thoughts on using Hardie Panel, cut to size? It's not designed for this, of course, but I wonder how well it will hold up. The best alternative I've found so far is galvanized roof panels, which will rust away eventually. The Hardie panels might last just as long -- and I'd use up leftover material cluttering my shed.