I have a wooded, sloped yard behind my house. Mostly the weeds and whatever else is there is pretty well-established and strong. Preen applications never did anything for me, but I'm not 100% certain I applied exactly the right amount, timing, etc. I use Ortho Total Vegetation Killer or Round-up Brush killer (concentrate) applied with one of those manual pump sprayer things. Usually takes two generous applications in the spring. Keeps it pretty bare - with just a few hardy survivors that pop up again in the fall. It helps to mulch deep - but that gets very expensive and time consuming. I only do it every 2nd or 3rd year and try to get at least 4 inches, but closer to 6 inches deep if I can. Having the mulch delivered in bulk, dumped in the drive and making several hundred (or it feels like it) trips with the wheel barrow then manually spreading is more economical -but takes me 2 1/2 days of work. My local supplier has a "blower" system where they can apply the mulch using a flexible hose, that's quick and easy for me but about 4 times the cost. My property is 1/3 acre, and I only do a portion (above the slope to the stream) the property goes from the street to across the stream, so I imagine I'm only talking about an area maybe 1/8 of the entire lot. I'm very bad at guessing how large a space is, so I'm sorry I can't provide a better size estimate of the area I'm talking about. Good luck.

Sherri