I recently watched a TV show on the National Geographic  network that talked about when the Europeans first set foot on this continent, they brought their cattle and horses with them and drove them westward across North America. When they beat down the native grasses with their livestock trails, what came up in its place? Why weeds, of course. So here we are centuries later, still fighting a battle with weeds. 

One weapon in the “War on Weeds” available to us today is something typically referred to as weed barrier fabric or weed block. There are many brands on the market, all claiming to save time and labor, as well as eliminate or reduce spraying of herbicides to banish weeds. Many times during the process of a landscape renovation job I get to uncover the previous attempts of weed block installation, from commercially available weed barrier cloth to garbage bags to visqueen, at all different levels of skill of installation. 

While weed barrier fabrics are a great tool to have in the arsenal they aren’t the “be-all, end-all” solution to weed prevention because they face many challenges in the harsh outdoor landscape environment. Some of these challenges are:

  • The ultra-violet rays of the sun. While it’s true, most of the time the fabric will be covered with mulch, rock, or shaded by plants, U.V. rays are know to be very efficient and can still cause slow degradation of the material over time which makes it more susceptible to tearing. Even if the fabric has U.V. protection built in there will still be some degradation over time from U.V. rays.
  • Mechanical disruption. Obviously if the fabric is compromised by a chunk of mulch getting plunged through by walk on it, working in the area on your knees, or a tool pierces though, you have an entry point for weeds.
  • Weight of aggregate materials vs. strength of fabric. Some stone products are either heavy per unit, such as a 3 ½ ” decorative river rock, or somewhat sharp, such as 3/4” marble chips. Some fabrics are only suited for mulch and if used with heavy or abrasive materials, will tear the fabric over time.
  • Noxious, aggressive weeds still penetrate fabric. In my experience certain weeds common to the Florida Suncoast have the ability to grow through even the best of the weed barrier fabrics and installation jobs. Nutsedge, Torpedograss, and Bermudagrass are especially noxious. I once conducted an experiment on a couple of beds infested with Bermuda and Torpedograss. After Roundup was sprayed twice to achieve a good kill, we doubled up on the heavy-duty ground cover fabric. Then a layer of red mulch was put down. The weeds actually grew through the fabric within six months! That is how aggressive these types of weeds are. 

Weeds grow on top of fabric. Through various environmental means, including the breakdown of mulch into finer organic material, dirt can appear on the surface of the fabric. Depending upon the species, weed seeds are also spread by various means in the landscape such as by lawnmowers, wind, birds, and walking through the planting bed. Inevitably some of those weed seeds may find their way into areas where there is a medium for growing. Most of the time the fabric does make it easier to pull these weeds since it prevents the roots from taking hold in the ground. 

Prior to installation of a weed barrier it makes sense to either mechanically remove or chemically exterminate the existing weeds. If using a herbicide like Roundup® you want to apply it, let the sun cook it in for a week, then reapply and let it set for another week. 

Even though the installation of weed blocks does not guarantee extermination of the pesky plant interlopers, when done correctly it is an environmentally friendly and labor saving tool that can greatly reduce weed growth.

When searching for an effective landscape fabric it is best to look for a stiff, heavy-duty polypropylene weave. Many of the brands I’ve seen sold at home improvements stores are too flimsy and tear easily. Professional grade geotextiles will perform better at fending off weeds. Contact your local landscaping company to see what product they recommend. 

So the good news is that even though we are still at war with weeds, our arsenal of solutions has grown with time. In future blog posts I will talk more about the different methods of weed control at our disposal. If you are in the Tampa Bay area, contact me for a FREE consultation so I can help you find the solutions to your particular weed problems.


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