I've started converting my lawn to a prairie with the intention of doing a little section at a time, using potted plants and plugs. The first section is a roughly 60x15 ft area which was planted 2 years ago.

The lawn that I'm replacing is weedy, with quackgrass and I'm now dealing with QG invading my prairie planting. I hand pulled last year and also placed a ~1ft buffer between the lawn and the prairie plantings, with landscaping fabric and mulch. This obviously didn't do anything to stop the QG.

My question: is there an effective barrier that I can use between the lawn and the prairie plants to prevent the QG from invading? Preferably something I can move as I make the prairie garden larger each year. Or, do I need to rethink doing a section each year, in favor of killing the entire lawn and seeding?