I made a HUGE mistake about six years ago in planting vinca beneath some paper birch trees. It has spread like crazy, totally engulfing other perennials (sedums, liatris, creeping phlox, siberian iris)and I have found it almost impossible to pull - especially now that it's hot and dry and the soil is rock hard.

Suggestions I've read on this forum include:

- smothering with newspaper (but this has become a rather large area)

- having a dig party to shovel up all the vinca (but I think this would do as much damage to the birch tree roots and don't really think it's a good idea)

Any thought on round-up? Might it harm the tree? Of course, I'd have to avoid area near the perennials and that may defeat the purpose in the long run...

any other thoughts?

thanks!