Grass – Growing on Stepping Stones
Q: How do I get the grass to stop overgrowing my walkway? The will begin to over grow the walkway and sidewalk within a week of trimming. I tried vegetation killer however the runners just spread over it.
A: One of the great advantages of bermudagrass is its ability to quickly spread and fill a bare area. In your case though, the bermudagrass is trying to fill an area you want to keep bare.
My best suggestion is to pick up the stepping stones and spread an area underneath, using pea gravel or slate chips, at least 6 inches wider than the stones on all sides and put the stones back into place.
Then you can spray glyphosate (click for sources) on the grass as it invades the gravel and before it covers the stones.