No..you still have to put some sort of barrier underneath or kill the grass/weeds underneath first...either by preparing the area first with layers and layers of heavy newspapers months ahead of time that has first been sprayed with Roundup..OR by using one of the weed blocking barriers that roll out. I usually spray and spread out a barrier a couple of days later. It would be so nice if simply mulch or chips worked...but it doesn't...the weeds just come right through.
