Natalie...
It seems to root and spread by itself. It spreads the same way that ivy spreads. It sends out runners and then tip roots.
As I said above, the vinca behind the rose is covering a vertical wall. I have never done anything to that area except to water it now and then. I haven't even cleaned out the dead growth caused by snow that stuck around longer than a few days. I haven't even fed it. The most I do to
that bed is trim around the edges.
I hope you don't mind, but I'll post that photo in this thread, too, so you don't have to go back and forth:
For the bed shown in the photo in the post above of the bed by the driveway, I have had to clear out a bit of native grass that tried to get into the bed, but I fed it a couple of years ago and the vinca grew in thicker. As you can tell, I don't spend much time caring for the vinca. I forgot to feed it this year
The star thistle has tried to grow around the vinca bed and in the rose bed, but has never invaded the vinca. I have a very small battle with the start thistle in this part of my garden.
Yes, I do think it will stabilize the slope and I agree that you will want to make sure it does not move into your lawn area. I made the deer cage larger this spring and the vinca you see in the photo below has since been removed because when I put up the cage, I put it across the base vertical wall and this photo was taken before I weeded and removed the vinca. The rose has no blooms because I disbud my roses every spring to keep rose curculio weevils from breeding in my garden.
Smiles,
Lyn