Tomf, the weeds are so prolific that I decided to spend a few years getting them dead before I add plants. 2 years ago I put plastic under the mulch. I pulled it from a small area this year and there was no life. I'll plant that spot because I do not plan to enlarge it. I am going to enlarge the mulch areas under the trees in the front two more times with plastic and mulch. So in 5 years I'll add plants. I HATE weeds.
When I have the mulch areas the size I want them, I'll leave the plastic one more year, yank it and then plant.