My Wife like lilacs, my yard is heavily loaded with Clay soil you can dig over 4 feet anywhere and still hit solid clay. I thought that might be causing premature root rot. Any suggestion on planting a lilac in this type of soil or are we just not going to be able to plant one? Previously I have dug a large hole much bigger than the plant I am planting, added crushed stone to the bottom, then filled it in with good topsoil mixture and then planted the lilac.