I was hoping that someone might be able to tell me the best way to go about killing the Russian Sage which is growing up through my 10 year-old Proteus. I am hoping that I won't need to dig up the clematis as it is one of my prettiest. I have tried to kill Russian Sage with Round-up, but it doesn't do the job. I have tried keeping the ground wet to make it uninhabitable for the Russian Sage, but to no avail. I have dug up the largest roots I can find that might be feeding the RS branches, but new sprouts keep showing up. Any suggestions would be greatly appreciated.