A weed barrier, often called landscape fabric, is a permeable material typically made from woven or non-woven synthetic fibers like polypropylene. Its primary function is to suppress weed growth by blocking sunlight from reaching the soil and to separate subgrade layers, preventing materials like gravel from sinking into the earth. The fabric is vulnerable to degradation from ultraviolet (UV) radiation and can be easily damaged by foot traffic or garden tools. Covering the fabric is necessary to protect it, ensuring its longevity and maintaining the aesthetic appeal of the landscape. The choice of covering material depends on the desired appearance, budget, and the level of long-term maintenance preferred.
Durable Inorganic Options
Inorganic materials are a popular choice for covering a weed barrier because they do not decompose and offer permanence. Stone products, such as river rock, pea gravel, and crushed granite, provide a clean, long-lasting surface with minimal need for reapplication. The heaviness of these aggregates helps anchor the landscape fabric securely to the ground, which is beneficial in sloped or windy areas.
A drawback of stone is its tendency to absorb and radiate solar energy, which can increase the temperature of the underlying soil, potentially harming plant roots in hot climates. Other inorganic options include manufactured materials like rubber mulch, often made from recycled tires, which is permanent and provides a shock-absorbing surface in areas like playgrounds. Rubber mulch can also retain heat and may release chemical compounds as it breaks down, which should be considered in planting beds. While inorganic coverings require little maintenance, their initial cost is higher than organic alternatives, and they are difficult and labor-intensive to remove if a future landscape change is desired.
Natural Organic Options
Organic coverings are biodegradable materials that naturally break down over time, making them a common selection for planted beds. Wood mulches, including shredded hardwood, cedar, and pine bark, are widely used for their aesthetic appeal and ability to moderate soil temperature. These materials help keep the soil cooler during summer and provide insulation during colder months, which benefits root health.
The decomposition process improves soil structure by adding organic matter and nutrients. These materials excel at moisture retention, reducing water evaporation from the soil surface and decreasing the need for frequent watering. Organic mulch can harbor wind-blown weed seeds that germinate directly in the mulch layer, requiring manual removal. As organic materials decompose, they require yearly or biennial replenishment to maintain proper thickness and function.
Installation Depth and Maintenance
Applying a sufficient layer over the weed barrier is necessary for performance and protection. The covering layer must be deep enough to completely block UV light, which degrades the fabric’s plastic polymers, and to prevent accidental piercing. For most applications, a consistent depth of 2 to 3 inches is recommended for both stone and mulch to achieve adequate coverage and weed suppression.
The maintenance requirements differ between the two material types due to their inherent properties. Inorganic materials, such as gravel or stone, require only periodic raking to redistribute the material and keep the surface level. Organic mulches have a reapplication cycle because they break down, requiring a replenishment layer every one to two years to sustain the 2 to 3-inch depth and continue shading the weed barrier.