Hi, I want to create a 5' wide landscaping bed that runs next to my driveway. Instead of mulching, I plan on planting a less invasive periwinkle (Vinca Minor Shugert) or Georgia Blue Speedwell. So on the West side of the 5' wide bed is the driveway and on the East side I want to create a boundary for the bed laying down a strip of river rock say 6" wide to keep the groundcover from the lawn

The groundcover will propagate in this bed bordered by the driveway and the river rock. I won't have nearly enough groundcover to start so my initial idea was to plant some clumps in the middle of the bed and let it spread on it's own in every direction. When it reaches the driveway, it'll have nowhere to go and when it hits the 6" wide area river rock to the East, I guess I will have keep fighting it periodically to keep it from growing past it into my lawn.

My question is this. If I plant all my starting groundcover abutted to the 6" wide border of river rock at the start (instead of the middle of the bed), will the groundcover "learn" early on that the path of least resistance is West and spend it's growth efforts in that direction so that after it fills out the bed and then hits the driveway, it will continue to try growing West with little success and not try to grow East where the slim border of river rock will be located and from where it started?

Or by abutting the starting groundcover to the river rock border, will it just grow West and still try to keep growing East as well so I'm better off starting off the groundcover in the middle of the bed?

Thanks JL