Whether Weed Cloth?

— Nan Sterman

While there are lots of great garden products on the market, some are questionable. Weed cloth is one of the questionable products. Is it good? Is it bad? Is there any reason to use it?

Weed cloth beneath a pot – one of the best times to use weed cloth

Weed cloth, weed fabric, weed barrier, and landscape fabric are all names for materials sold by the roll or sheet, to be laid atop the soil with the vague promise of stopping weeds; but does it? And if it does, is it the best way to stop weeds?

Weed basics

All soil contains weed seeds – at the surface, below the surface, often several inches deep. That’s just reality. When temperatures are right and there’s enough moisture in the soil to “activate” seeds, they germinate and start growing. In our climate, spring is typically the weediest time if year, once the soils warm after fall and winter rains, but weed management is a year-round task.

The idea behind weed cloth is that you spread over the soil to eliminate weeds. To some extent that is true. Once weed seeds germinate, those tiny sprouts need sunlight so they can photosynthesize and make the energy to grow. Weed cloth keeps sprouts in the dark so they soon die from lack of sunlight and therefor, lack of energy.

Weed Cloth vs Mulch

Mulch, like weed cloth, keeps weeds in the dark so they die from the inability to make energy.  But mulch does much more than weed cloth.

Weed cloth is pretty ugly, so we hide it under a layer of mulch. But did you know that mulch alone accomplishes the same thing? Mulch not only keeps weed sprouts in the dark, it has the added value of nourishing both beneficial microbes and decomposers that live in the soil. Mulch also improves the drainage of heavy soils and the water holding capacity of fast draining soils. As mulch breaks down, it releases nutrients that eventually benefit plants, too.

Weed cloth laid out between mulch and soil acts as a physical barrier so the soil gets none of the important benefits from mulch.

Weed Cloth Short Term vs Long Term

Bermuda grass, with its fleshy white underground stems, will eventually sprout and push up through weed cloth

Aside from seeds, pernicious weeds like Bermuda grass eventually penetrate weed cloth. They

grow up along edges, poke out between seams, and as weed cloth starts to break down, weeds grow up through holes that develop. Soon, we gardeners are left with a mess of tattered black cloth to pull out and get rid of. Not fun.

Some contractors see a short-term benefit in using weed cloth to finish a project so it appears as if all the weeds are gone. But long term, those weeds will come back to haunt you. And you will have spent money on something that is a total unnecessary.

All of this work, by the way, is targeted at weeds coming from the soil. Nothing stops weed seeds from blowing in on the wind, arriving with bird poop, falling off your shoes or dropping off your dog’s fur. Weeds, like dishes and laundry, are inevitable. But weeds don’t root very tightly in mulch, so they are easy to pull when you see them.

Seeds of grassy weeds like these blow into gardens, drop in from bird poop, walk in with your shoes, or fall off your dog’s fur.  It’s inevitable!

A Role for Weed Cloth

Is there a place for weed cloth? In my little backyard nursery, I use the thickest weed cloth under pots so plants don’t root through their pots into the soil below. Beyond that, I wouldn’t waste my time or money.