The disadvantages of using landscape fabric Chris Enroth University of Illinois Extension Special to McDonough County Voice, USA TODAY NETWORK MACOMB — Landscape fabric. It’s what goes under the mulch. Right? I’ve had several conversations with home gardeners looking for a permanent solution to keeping the weeds down and each time I warn them about the use of landscape fabric. If you’re thinking, “Hang on! Landscape fabric doesn’t work?” You’ve seen people on TV and perhaps watched professional landscapers roll out the black landscape fabric before spreading mulch. And why does every garden center sell the stuff if it doesn’t work?