Landscape fabric is a permeable material. Its primary function is to suppress weed growth by blocking sunlight from reaching the soil beneath. Covering the fabric is a necessary step to ensure the longevity of the barrier and the finished appearance of the landscape.
The Requirement for Covering
Covering the installed landscape fabric with a top dressing is mandatory for both functional and aesthetic reasons. The synthetic fibers are highly susceptible to degradation from ultraviolet (UV) radiation in sunlight, which causes the material to become brittle and reduces its lifespan. A layer of ground cover also provides necessary stabilization, preventing the lightweight fabric from shifting due to wind or foot traffic. Finally, covering the fabric creates a clean, finished appearance that integrates the weed barrier seamlessly into the overall landscape design.
Mineral and Stone Cover Options
Inorganic options like stone and crushed mineral aggregates offer a long-term, low-maintenance solution for covering landscape fabric. Materials such as pea gravel, decomposed granite, and river rock are popular because they do not decompose and rarely need to be refreshed. Stone covers offer excellent resistance to wind and heavy rain, minimizing the risk of the material washing away. When choosing stone, select rounded materials like pea gravel to minimize the chance of sharp edges puncturing the fabric. A drawback is that mineral covers do not contribute organic nutrients and can absorb and retain solar heat, potentially stressing plant roots in sunny locations.
Organic Mulch and Wood Chip Options
Organic materials, including shredded hardwood, cedar, cypress chips, and pine straw, are frequently used to cover landscape fabric. These options are valued for their aesthetic appeal and their ability to moderate soil temperature. The insulating properties of organic mulch keep plant roots cooler during the summer and help prevent rapid temperature fluctuations. As these materials naturally decompose, they release nutrients back into the soil, improving its health. However, their ephemeral nature requires annual or biennial replenishment to maintain depth. If not maintained, decomposed mulch can accumulate on top of the fabric, allowing wind-blown weed seeds to germinate.
Recommended Depth and Installation Tips
Recommended Depth
The correct depth of the top layer is important for both fabric protection and effective weed suppression. For inorganic stone and gravel, a layer of two to three inches is recommended to fully conceal the fabric and provide sufficient weight. Organic mulches should be applied slightly deeper, generally three to four inches, to allow for natural settling and decomposition.
Installation Tips
Prior to adding any covering, the landscape fabric must be secured to the ground using landscape staples or pins, particularly along seams and edges. Using a physical edge restraint, such as metal edging, pavers, or a spade-cut trench, is necessary to keep the covering material contained.