Need some advice/help: A customer of mine has Spreading Junipers that cover an entire bed. They are huge. It looks like a huge blanket of spreading Juniper. These border up against the house and are all in the front bed. He has grass of course all on the front lawn. He wants a "clean edge" in transition from the Junipers to the grass. What kind of materials can you use to switch from the grass land to the Juniper? He put down a real small maybe 3" swath of rock to make a distinction, but grass grows into the rocks and after a few weeks, the rocks are mixed into the grass, it's not a clean edge, etc. Without the rocks, where do you draw the line? The juniper spread, battle for ground with the grass and it's not easy to make a clean trim. Any transition ideas for this kind of thing? Thanks!