Yes, landscape fabric will kill some grass if applied to grass that has been cut too little, and then more material is applied over the landscape fabric to block light. Landscape fabric is ineffective at killing grass on its own if applied in a single layer, as the manufacturer usually recommends. In these cases, landscape fabric is placed on the lawn as a way to speed up the process. The landscape fabric keeps vital sunlight out so that the grass can die under it.
The application of non-organic materials, such as pea gravel, will also do. Garden cloth shouldn't be a permanent solution, as mulch, soil, and other organic materials will break down landscape fabric over time. This will lead to weed growth and more grass growing through the cracks. Landscape fabric is useful for many different landscape projects.
Not only does it suppress future weed growth, but it also suffocates existing vegetation and eventually kills it. To turn a neglected lawn area into gravel mulch, simply lay the cloth and spread the pea gravel on top; the grass will die and decay instead. I placed some and covered it with rubber bark for my children's play area on a dirt surface, and within a month there was grass growing through the cloth and rubber bark. If you choose to cover a large area with landscape cloth (such as a flower bed or around trees), make holes in the fabric where the plants will go to allow their roots to access the soil below.
The purpose of garden cloth is to control weeds, and it is sure to do its job effectively for the first or second year, but be prepared to pull out any weeds that may sprout on top of the fabric later on. It's a myth to suggest that either product would kill insects on the ground unless you put it in a bucket, they'll just crawl around it. Even so, plastic has its place in the landscape for projects such as installing pavers or cobblestone walkways, using plastic landscape sheets just above the ground will prevent weeds from growing between the stones and offers a permanent solution. Landscape cloth (which is usually black) also helps plants grow in some situations because it warms the soil.
Adjust and secure it with landscape clips, using as many as you need to ensure a perfect fit on the lawn. Once you are satisfied with the way the fabric is placed, secure it with garden stakes or staples every 1 to 3 inches, depending on the size of the space. Brian Barth works in the fields of landscape architecture and urban planning and is a co-founder of Urban Agriculture, Inc. If you use landscape fabric in the same places where you grow plants, of course, it's not suppressing weeds, probably because you make holes for your plants.
