Weed fabric, weed cloth, weed barrier, landscape fabric – whatever you call it the idea is the same. Cover the ground with weed fabric and put mulch or rock on top and you’ll never have to pull another weed. Or, if you are more of a realist, you’ll have much less weeds to pull.
The truth is weed fabric rarely works and is sometimes a really bad idea.
Weed barrier may control weeds for a season or maybe two, but after that weeds will seed in the top mulch or rocks. If you have bark mulch, the weeds are happy to seed there and root through the fabric. If you have landscape river rocks on top of the fabric, plant debris sifts through the rocks and settles on top of the fabric. This debris becomes a nice, protected compost and weed seeds sprout easily.
Weeds that have long stretches of roots, such as bind weed, will come up wherever there are seams in the fabric, at the edges of the fabric, and in the holes that were cut for the plants. All of these weeds are much harder to remove. When you pull a weed that has rooted under the fabric, you’re often unable to get much of the root. This means the weed will be back shortly!
Finally, if you’re planting perennial plants that you hope to spread and proliferate, limiting their access to the soil via weed fabric is counterproductive.
Horticulture researchers at CSU are outspoken in their dislike of weed barrier:
Black plastic (polyethylene) and woven plastic weed barrier fabrics (polypropylene) are not recommended as a mulch in landscape areas. Black plastic is impermeable therefore no oxygen exchange can occur to the soil. Lack of oxygen to the roots and soil microbes significantly reduces plant growth. Black plastic also prevents water penetration. Woven weed barrier fabrics initially allow some minor oxygen and water exchange to the soil, but eventually become clogged and create the same issues as plastic. Weeds easily germinate on top of the fabric and root into or through it. Both plastic and woven plastic fabrics disrupt the life cycles of many pollinators and other soil invertebrates. Fabrics and plastic can be good choices for large-scale vegetable production where regular maintenance and replacement is easily performed. In most gardens and landscapes, the correct application of other mulches is a better option.
Klett, J.E. Mulches for the Home Grounds, Colorado State University Fact Sheet No. 7.214, December 2020.
Landscape fabric does have a place and purpose! Fabric is great under hardscape, such as under compressed gravel walkways, under paver patios, or under landscape rock used in shrub beds. In these areas, the purpose of the fabric is to separate the aggregate from the soil, keeping it from getting muddy.
I doubt weeding is anyone’s favorite chore. Sadly, there is no magic wand to keep weeds out of your flower bed.
