We’ve all heard how excellent landscape fabric is in gardening to prevent weeds. But there’s a hidden truth about using it that few are aware of …
As a whole, it’s ill-advised to use landscape fabric or weed membrane under gravel or other mulches in gardening. It traps air and moisture, suppressing weed growth but suffocating the soil, leading to poor plant growth. The fabric also degrades over time and needs replacing every 1-2 years.
Below, I talk about this more in detail and why landscape fabric is more harmful than anything:
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Table of contents
What is Landscape Fabric?
It’s a sheet that blocks sunlight to prevent weeds and soil erosion; some are permeable, allowing water and air to pass through. It’s often layered with mulch like gravel, wood bark, and topsoil – primarily to hide the fabric away. Depending on the thickness and material type, various landscape fabrics will have different porosity and durability. Because of this, they are often preferred over black plastic.
They are commonly used in hardscaping, i.e., man-made structures added in an area such as paved pathways, driveways, and retaining walls. But they are also used in softscaping, i.e., ornamental landscaping around trees, shrubs, and perennials. You’ll unlikely see it used for short-lived plants like annual flowers or spreading ones like groundcovers. However, over recent years, it has been found that using landscape fabric in your garden has proven to be troublesome in the long term.
Here are some issues that pop up:
- Landscape fabric will not stop windblown weed seeds from growing, especially if mulch is on top. For the first 1-2 years, the material will effectively suppress potential weeds underneath, provided existing ones have been pulled out. But not the ones on top. When these develop, they will grow through the fabric. So when you pull them out, you’ll rip through the material, which needs to be changed with a new one asap.
- The soil underneath the landscape fabric becomes slimy and stinky, leading to poor plant growth in the surrounding area. Despite the material’s permeability to water and air, the small holes will get clogged with soil particles and tiny dirt debris over time. This won’t allow the plant roots to breathe, cutting off the essential gas exchange and giving rise to mold and mildew problems.
- Landscape fabric will eventually break down in 1-2 years. Nothing is meant to last forever and replacing this material is a big hassle, especially if you have it spread over a large, grassy area. A lot of work goes into it, and if you’re not in a position to hire a landscaper to do it for you, it’s going to be long before you get the entire thing out.
- Mulch will eventually give way to show the ugly landscape fabric at the bottom. This is more concerned with aesthetics than functionality. But either way, who wants to see a flapping sheet bunched up on the ground in your garden? It’s not exactly a pretty sight.
In short, using landscape fabric to prevent weed growth in your garden is inadvisable. In fact, it’s one of the many myths that have been debunked! Dr. Linda Chalker-Scott discusses this well in this short article. Sadly, not many people know about this. And it doesn’t help that you’ll come across so many sites on the internet saying how it’s a good investment.
Can I Place Landscape Fabric Underneath Gravel Mulch?
The short answer is no, mainly if it is used beneath a decorative gravel mulch around plants to suppress weeds. As mentioned in the previous section, it’s an ineffective long-term weed barrier. It will also make your plants suffer due to inadequate airflow and water.
However, you can use landscape fabric for gravel paths and walkways in the garden, away from plant growth. This is more of a DIY option when doing your own landscaping as opposed to using concrete or more stones. It’ll help prevent soil erosion and the rocks from sinking into the ground. But remember, this won’t prevent weeds forever; you’ll need to hand-pull out any that appear later.
Non-woven and spun landscape fabrics are the best types for pebble mulched trails because these are often more durable. They can also work as a quick fix to protect plant roots in windy areas. But this is not ideal in the long run – you’re better off planting elsewhere or creating a windbreak hedge.
Apart from using it for your rocky tracks, there’s no upside to laying landscape fabric where plants are concerned in your garden. You’ll just be creating grievances and too much work for yourself over time. It’s best to stop using the material altogether and hire a certified landscaper that doesn’t use it either.
Frequently Asked Questions about Using Landscape Fabric Under Gravel
Non-woven or spun landscape fabric is the best option to place underneath gravel mulch for man-made structures like pathways and driveways. Using landscape fabric in ornamental landscaping is generally unsuitable because it’ll impede gas exchange for plants’ roots, leading to poor development. Landscape fabric should only be used for hardscaping where no plants are involved.
It may be helpful to lay a weed membrane below a gravel layer to prevent the stones from descending into the ground. But it will also lead to improper plant development due to limited air circulation to the roots. A better alternative would be to forgo gravel mulch and landscape fabric for organic mulch, such as pine bark and wood chips. These have the benefit of breaking down and adding nutrients to the soil.
Thin, woven, and perforated landscape fabrics are permeable, allowing water and air to pass through into the soil. But these usually have low durability and must be changed often over the years due to persistent weed growth. The tiny pores will also get blocked over time, causing a lack of airflow and trapped moisture.
Landscape fabric or weed membrane will help keep gravel or pebbles from sinking into the ground, preventing soil erosion and weed growth. However, as the material naturally deteriorates, you will need to substitute it every 1-2 years with a new one. Remember, the thinner it is, the faster it will degrade. A better alternative instead is to add larger stones below and top them with smaller rocks
Adding more rocks or applying concrete is ideal for suppressing weed growth permanently. Alternatives such as herbicide and landscape fabric will require repeated application frequently. They are both generally bad for the soil and work more as a temporary fix.
Tarpaulin should never be used to replace landscape fabric because it is a waterproof material. It’ll instantly prevent air and moisture from entering the soil, while the latter is temporarily effective in the first 1-2 years. Some may be porous, depending on the material. However, in the long run, either tarpaulin or landscape fabric should not be used as a weed barrier because it is more troublesome than anything.
Final Words
All in all, the general use of landscape fabric is plain bad news in gardening. But when it comes to layering it under gravel mulch for paths and walkways, it can be pretty valuable. Where possible, use more stones or concrete instead to keep those weeds away forever. Happy planting!
References:
- Weed Management in Landscapes Management Guidelines–UC IPM. (n.d.). Ipm.ucanr.edu. Retrieved September 14, 2022, from http://ipm.ucanr.edu/PMG/PESTNOTES/pn7441.html
- Landscape Fabric | Nebraska Extension. (n.d.). Extension.unl.edu. Retrieved September 14, 2022, from https://extension.unl.edu/statewide/dodge/landscape-fabric/
- The disadvantages of landscape fabric: University of Illinois Extension. (n.d.). Extension.illinois.edu. Retrieved September 14, 2022, from https://extension.illinois.edu/blogs/good-growing/2021-06-25-disadvantages-landscape-fabric
- Chalker-Scott, L. (n.d.). Retrieved September 14, 2022, from https://s3.wp.wsu.edu/uploads/sites/403/2015/03/landscape-fabric.pdf
- Chalker-Scott, A. L. (2019, September 10). Landscape fabric – a cautionary tale. The Garden ProfessorsTM. https://gardenprofessors.com/landscape-fabric-a-cautionary-tale/
- Should I use landscape fabric to keep weeds out of my perennial garden? (2019, May 4). Extension. https://extension.unh.edu/blog/2019/05/should-i-use-landscape-fabric-keep-weeds-out-my-perennial-garden
- Salinas, M. (2019, October 22). Landscape Fabric: A Good Option for Controlling Weeds? Gardening in the Panhandle. https://nwdistrict.ifas.ufl.edu/hort/2019/10/22/landscape-fabric-a-good-option-for-controlling-weeds/
