Types of weed control barriers
The most commonly used weed barrier is a permeable fabric-like plastic that will let some water down into the soil below it. Others are just black or clear plastic. Some of the weed barriers are chemically treated to be UV resistant, so they won’t break down in direct sunlight as easily.
How does the barrier work?
Essentially, the weed barrier works by brute force by keeping the weeds from being able to grow through the cloth/plastic. In theory, if the area is covered then it will also prevent sunlight from reaching the weeds so they can’t grow. In practice, this isn’t usually the case.
The damage cloth weed barriers can cause
These physical barriers won’t just block weeds, they also block water, beneficial insects, and nutrients from getting to the soil. In a natural environment, the ground will have nutrients from organic matter such as leaves breaking down to feed the soil, which would be prevented with a weed barrier.
Earthworms also need to reach the surface. They help break down matter in the soil, as well as alleviate compaction. Weed barriers prevent proper biological activity from taking place in the soil and prevent proper drainage.
Why it doesn’t work that well in most cases
Weed barrier clothes are not a great option for gardens, or any area that you would like to grow plants, as the barrier will prevent proper bio-activity in the soil, making the soil unsuitable for plants. The barrier also does not let enough water reach the plants. If the barrier is letting enough water though, the chances are good that it is also allowing weed growth.
Many plants, including, trees (suckers), shrubs and weeds will manage to grow through the fabric, leaving it tattered and no longer useful. The roots of your perennials, tree and shrubs can get entangled in the barrier and not grow down into the soil like they should.
Even though the fabric might prevent some weeds from coming up through the barrier, it won’t prevent weed seeds that have blown in from germinating above it; the roots will then penetrate and grow down through the cloth barrier. Any organic material on top of the weed barrier will serve as the small amount of soil that the weeds need to germinate on top of the fabric.
And have you ever tried to plant in an area where there is existing weed cloth? What a nightmare!
Weed barrier fabrics are best suited for areas that will be undisturbed such as rock areas or hardscaped areas. But even then, there are better options.
Are there any good uses for landscape cloth barriers?
There are a few beneficial uses for these barriers. One case would be an annual garden, where the entire garden will be removed at the end of the season, along with the weed barrier, and replaced and replanted the following year. In this scenario, the weed barrier is completely removed after one season.
Another scenario would be an area of the property that is not meant to grow anything, such as river rock bed
Alternatives to a landscape cloth barrier
You can hand pull the weeds that come up through your rocks and mulch without worrying about adding more plastic to the environment. It can be tedious, especially if you don’t get the whole root. But this is a good option, especially for vegetable gardens.
If you don’t want to fuss with trying to pull weeds, you can use a pre-emergent weed control. The pre-emergent that Organo-Lawn uses will last a full season. We apply it during the winter; this will help keep winter annuals as well as spring annuals from germinating. This pre-emergent spray won’t affect perennials; those will need to be killed with a post-emergent. But once those have been knocked out, you should only need to use the pre-emergent weed control, done once a year.
Since this weed control is a synthetic product, we will not apply this in vegetable gardens, so hand weeding in these areas is still advised.
Ground cover plants or a thick layer of mulch in your gardens made from wood chips, pea gravel, stones, etc. will work far better than any “magical” weed barrier that ends up causing more harm than good in the long run.