It's a late start but we've finally got the greenhouse on the go.

Inside we are going to created beds along the perimeter walls that will be about 18" deep. They won't have bottoms because I would like the plants to be able to grow deep if they choose to. :)

Anyway, we are building the greenhouse over an area where there is currently grass (it was never really taken care of other than being cut, we have too much grass to baby.) Should I remove this grass before I fill the beds? Or can i just do a quick till to loosen the dirt and grass and pile my dirt on top?