Try the Cinnamin Bark powder. I t works pretty good, and with a lot that size, you can stay on top of it.
I personally would tear up, that one section that is nothing but CG, and keep it clean until seeding time.
Whatever you do... don't let it go to seed...
Water/air ratio in relation to water flow to/from any plantlife is a Basic Fundamental Concept in understanding seed germination as much as transplanting a 20' Maple tree in 90 degree weather...