How long do I need to leave the black plastic on my prepared garden rolls to kill grass pieces. Grass is not rooted. I made an area in my backyard to plant a garden. I have thick grass and I did not dig it up and just tilled it. NOW I have all this grass that will grow if I don't kill it. I don't use chemicals. I raked and took out a lot of the grass that is broken up with big roots, but there is still plenty of grass. I tilled and tilled until dirt was powdery and then made rolls/hills and again picked out some of the grass with roots. I then wet ground and covered with black plastic.
Certified GKH Gardening Expert
Usually about a month or so is adequate for killing the grass.