I remember reading yrs. ago when I planted my first black walmut that certain plants won't grow under them, and I believe I recall that you should be careful with the leaves, also??? My new place has like 10-12 huge black walnut trees. I was raking up yard yuck to layer into wood raised bed boxes this weekend when I was there so it could decompose over the winter...No walnut leaves at this point, but bark??? I thought I better hold back until I check this out. Thank you.