I have been so very impressed with some purple vetch that when started in the fall grows to a good meter high and 1.5 meters wide, holds up through mild winters, is dense for wind protection, then dies back in May'/June leaving straw-like residue that completely blocks weeds, and it sets nitrogen! And where I am the weeds live off the fog, so they are TOUGH stinkers. I have to water the vetch in the fall because we don't get rain, and if left to its own devices it will start midwinter on its own, but that's too late to block weeds. A row I planted with the vetch 18 months ago, untilled, this spring has no weeds where the vetch was! All around it they could be knee high if I wasn't mowing them.
"Life flows on within you and without you"...George Harrison
Coastal California, USA, Mediterranean climate - no summer rain, a little frost mid-winter