Brassica Question

Hello everyone, I planted a brassica plot about a week and a half ago and it is coming in great. The field I planted it in was mainly indiangrass,not sure if thats its true name or not but thats what i've always called it, before I tilled it over and disced it up. I was going to spray it with gly but decided not to because I figured if the grass grew back in between the brassicas it would just provide more cover for the deer while they fed. Now im starting to second guess myself and im worried the grass may grow to fast and prevent my brassicas from getting enough sun.Any thoughts on this? At this point my brassicas are about 1 1/2 inches tall while the grass is up to 6+ inches in some spots,but its very thin, not a whole lot of grass came back.Thanks for any suggestions

Also, does anyone know where I can find winter rye in the sc part of the state, I cant find it any where and dont want to pay 3 times more to have it shipped from somewhere on the internet.