I have a black walnut(Juglans nigra) stump. The tree was cut down six years ago. My understanding is that the juglone is no longer active one year after the tree's death. This may or may not be the case. I would have the stump ground out, except that there is a redbud in very close proximity to it. Does anyone know of any perennials, mosses, ferns or anything else that favor black walnut stumps as growing sites?