That will work if there is nothing left that you want to keep. The way I got rid of Chamaeleon Plant was the hard way. Digging up big chunks and removing every bit of rhizome I could find. Anything that it had grown through got bare-rooted and cleaned out. What. A. Job! It still took about a year to get all of it. Fortunately it wasn't that big a patch, but still. The Dwarf Plumbago was a similar chore. Live and plant and learn.
