I searched "plants" in Chief Architect Design Pro and got six results. The only actual direction given was how to place a plant. Zero results for "ground cover" or "multiplier". There is a brief landscaping tutorial but this is not included there either.
That said, here is the work around I discovered. Place the plant in an open area, away from garden beds and not touching anything else. Right click and choose "save to library" then name the plant. Then save your file. Now choose the plant from the User Catalog. I first placed it in front of the garden I want to put it in, raised it to garden level, then moved it onto the garden bed where I wanted it.
I hope this helps!
