I have a bed of Improved Golden Sedum that is healthy in every way, but wants to go back to lawn. This is difficult to weed, because the grass has a very dense shallow root system, while the Sedum has soft thin roots. Pulling the grass would take out a large part of the Sedum, and leave holes in the ground. How can I successfully remove this grass while maintaining the Sedum's health?
Here is a picture of how it looks after weeding. It is normally dense and tall.