Weed-kill:Geotextiles have major drawbacks

Tag : Non-Woven Fabric

One of the longest-running battles in the history of gardeningcould be titled "Gardener vs. Weeds".
There are many compelling reasons to prevent, eradicate or at leastcontrol the weeds that seek to compete with our desired plantings.However, when the method of control is more harmful than the resultobtained, such as in widespread applications of chemicalherbicides, it is time to take a look at alternate practices toachieve our goals.
One of the more recent innovations in the war against weeds is theuse of geotextile fabrics. A geotextile is typically defined as anypermeable textile material (fabric) used to increase soilstability, provide erosion control or aid in drainage. Geotextileshave been in use for thousands of years dating back to the Egyptianpharaohs.
Commonly called landscape cloth or weed-barrier film, moderngeotextiles are usually made from a synthetic polymer such aspolypropylene, polyester, polyethylene or polyamide. Geotextilescan be woven, knitted or non-woven. Varying polymers andmanufacturing processes result in an array of geotextiles suitablefor a variety of civil construction applications.
The property of allowing water and air to pass through whilepreventing weeds from coming up through it make landscape clothseem like an ideal solution for weed prevention. As a replacementfor the use of polyethylene sheeting under bark, it appears to be avast improvement.
Much of my work as a landscape contractor involves renovatingexisting landscapes that have either become overgrown, have beenneglected, or are generally not thriving for various reasons. Ihave been involved with projects that have had landscape cloth andweed-barrier fabrics installed for differing lengths of time and inevery case where I have encountered them, I have run into the sameset of problems.
Raking off the covering and peeling the cloth back invariablyreveals a dead, lifeless-looking and hard, compacted soilunderneath. And this can take place in as little as a couple ofyears! Perhaps the most disheartening fact of all is seeing thetrailing patterns made by earthworms as they tried and failed tofind a way through the fabric.
I have several serious concerns about these cloths. The first isthat although they are permeable, they seriously limit theinfiltration of air and water into the soil, and that is a hugedrawback. Organic mulches, if over-applied, also slow the passageof air into the soil, but their advantages greatly outweigh thenegatives. The cloths are not UV-resistant and need to be coveredto prevent solar degradation. In time, the finer particles of themulch work their way into the surface of the cloth and fill in thepores, further impeding its porosity.
Planting through the cloth involves making slits in the materialand getting dirt all over it, which is a hassle at best. Anythingthat stifles the desire to go out to plant or makes gardening lessfun rates low in my book. As soon as dirt gets spread on thesurface, weeds invariably begin to grow. And speaking of weeds,while the barriers do a good job of preventing annual weed seedsfrom growing through the cloth, they do not prevent weeds fromsprouting and growing in the covering mulch. It seems that rootsare able to grow quite well down through the cloth. If you have notkilled tough perennial weeds beforehand, you may find you stillhave to deal with blackberries, dock and thistles.
The biggest drawback to using these products, in my opinion, isthat they completely block the entry of organic matter into thesoil. It effectively stops the assimilation of leaf debris,decomposing bark or a topdressing of compost into the soil. Thatalone would negate their use for me. Add in all the other factorsand you won't see me applying them in my yard.
There are two cases where I will use them: as a liner under valveboxes to prevent soil from entering them and as an underlayment forlarge particle rock mulch, as in a dry streambed. Althoughattractive at first glance, I have found the use of geotextilecloths to be a disadvantage in most landscape applications.
Stan Mapolski, aka The Rogue Gardener, can be heard from 9-10 a.m.Saturday mornings on KMED 1440 AM and seen in periodic gardeningsegments for KTVL Channel 10 News. Reach him atstanpolski@gmail.com.