The sticky subject of weed mat...

(Another post by Glen...)

Controlling weeds has been a problem since the Garden of Eden… About 25-30 years ago, many years after the days of Adam and Eve, weed barrier fabric was introduced to the landscape market. It was, of course, billed as the “solve all” for all weed problems in planting beds. This new weed barrier fabric had the distinct advantage of allowing the water to actually get to the plant roots while stopping most weeds from coming up. At the time, the main material used in planting beds was some form of gravel, lava rock, or big chunks of pine bark placed on top of a layer of black plastic. Therefore, this weed fabric was a much needed improvement over the black plastic that was the industry standard. The black plastic seemed to work very well but it got holes in it when you walked on the gravel and the weeds always found the holes. Also, this black plastic was not then and is not now suitable for planting! The new fabric was really a very good product and still works very well under gravel, lava rock and such materials.
Then came the guy that invented the use of wood mulch, rumor has it he was related to the guy who started bottling water and selling it for the same price as sodas. Not sure who this guy was, but before about 25 years ago all the bark that was stripped off of logs during processing was a waste product and was pretty much wasted! Suddenly, this mulch product started taking over the market for planting beds. It was cheap, good for the plants and soil; and for the landscaper, it became “reoccurring revenue”. (You are supposed to refresh, replace your mulch every year or so)
Landscaper bright idea: This new “weed barrier fabric” would be great to put under mulch, would control the weeds and life will be great… wrong! After about a year or two we realized that the weeds were actually growing on top of the weed barrier fabric! The properties that made the mulch good for the plants, mainly that it decomposed and improved the soil, also provided the perfect “potting soil” for weed seed to germinate. The mulch that did not blow away, exposing the weed barrier fabric, turned into the organic matter but never really got down to the soil to help the plants. So we still use weed barrier fabric; in fact, do not put gravel down without it. But do not use it under mulch!  We typically use a pre-emergent herbicide when we use mulch. Put it down every season, and then spray the weeds when they are small enough to “melt” away. After you break the cycle of the weeds reseeding themselves (and control the weeds in the lawn), the mulch works very well without the weed barrier fabric.