Landscape fabric, often called a weed barrier or geotextile, suppresses unwanted plant growth by blocking sunlight. Yes, it can be placed over existing grass; this technique is a common method for grass suppression and preparing new garden beds. Success relies on selecting the correct fabric and performing a meticulous installation process. The fabric acts as a physical barrier, smothering the underlying turf by preventing photosynthesis.
Before laying the fabric, prepare the existing grass to ensure maximum smothering effectiveness. Mow the lawn to the lowest possible setting to reduce plant material. Clear the area of large sticks, rocks, or sharp debris, as these objects can tear the material during or after installation.
Once the area is clear, lay the fabric tautly across the ground. Strips of fabric must overlap significantly, generally six to twelve inches, to prevent grass from finding a path through the seams. This overlap acts as a barrier against emerging grass blades attempting to grow toward the light source.
To keep the fabric securely in place against wind and shifting soil, metal landscape pins or staples must be used generously along all edges and seams. Placing a pin every two to three feet provides adequate anchoring, which prevents the fabric from shifting and exposing the grass underneath. Immediate covering of the geotextile is necessary to protect it from ultraviolet (UV) radiation, which rapidly degrades the material and reduces its lifespan. A layer of organic mulch or stone aggregate placed directly on the fabric will block the sunlight and complete the installation process.
Factors Affecting Fabric Effectiveness and Lifespan
While effective at suppressing existing grass, landscape fabric does not eliminate the possibility of new weed growth over time. Airborne seeds can land on the layer of mulch or gravel placed on top of the fabric and germinate. Over time, decomposing organic matter, like leaf litter or fallen debris, creates a thin layer of soil above the barrier where these new weeds can establish roots.
When new weeds sprout, their roots often penetrate the fabric structure, making manual removal difficult. Pulling a weed frequently results in tearing the fabric, creating a new opening for grass to emerge from below. Removing rooted weeds often necessitates cutting the fabric, which compromises the barrier’s integrity.
The fabric’s impact on soil health is another consideration, as some types impede the natural movement of water and nutrients. Fabrics with lower permeability may cause water runoff during heavy rain instead of allowing slow infiltration. Furthermore, the fabric prevents organic material placed on top, like wood mulch, from decomposing and incorporating beneficial nutrients into the underlying soil structure.
The fabric’s lifespan is a limiting factor; most materials only last three to five years before breaking down, even when covered. As the fabric deteriorates, it becomes less effective and more difficult to remove in large, intact pieces. Replacing the degraded material requires removing and reapplying the entire covering layer, which is a significant maintenance task.
Other Methods for Clearing Grass
For those who find landscape fabric maintenance undesirable, several other methods exist for clearing a grassy area. One technique is solarization, which involves covering mowed turf with a clear plastic sheet that traps solar heat. This process “cooks” the existing grass and weed seeds by raising the soil temperature to lethal levels over four to six weeks.
Manual removal is the most direct and immediate approach, involving the physical digging up of the sod using a shovel or a sod cutter. While labor-intensive, this method instantly prepares the ground for planting and removes the entire root system of the existing grass. A more passive, biodegradable alternative is sheet mulching, which uses layers of cardboard or newspaper to smother the grass. The cardboard blocks sunlight and eventually decomposes, adding organic matter to the soil, though this process takes several months to fully kill the turf.