Landscape fabric, often called a weed barrier, is a permeable material designed to suppress unwanted vegetation by blocking sunlight while still allowing water and air to pass through to the soil below. This barrier reduces the need for chemical herbicides and conserves soil moisture by limiting evaporation. For the fabric to function effectively and reach its full life expectancy, correct installation is paramount, especially identifying which side must face upward toward the sun and which side must contact the soil.
How to Identify the Correct Fabric Orientation
Determining the correct orientation of landscape fabric depends primarily on the material’s construction, which is typically either woven or non-woven. Woven polypropylene fabric, the most common type, usually has one side that is noticeably rougher or fuzzier than the other. This fuzzy side is intended to face down and make direct contact with the prepared soil, as its texture helps the material grip the ground and prevents shifting.
The smoother side of woven fabric is almost always treated with a specialized ultraviolet (UV) inhibitor to prevent the sun’s rays from quickly degrading the material. This UV-treated side must face up, or the fabric will break down prematurely, potentially turning brittle and tearing within a single season. The smooth, UV-protected top surface is also engineered to allow water to funnel efficiently through the weave and into the soil.
Non-woven or spun-bond fabrics, which look more like felt, tend to be more uniform and may not have a clear fuzzy and smooth side. If the fabric has a colored side, such as black and lighter gray, the black side often contains the UV inhibitor and should face upward. If the fabric is a dual-layer material, the side designed for water permeability and UV resistance must be on top. In all cases, the side with the UV inhibitor is the definitive top surface and must be exposed to the elements.
Ground Preparation Before Laying Fabric
Before unrolling any landscape fabric, the underlying soil must be meticulously prepared to ensure the barrier’s long-term success and prevent damage. The first action is to remove all existing vegetation, including weeds, grass, and their entire root systems, by digging them out completely. Remaining root fragments, especially from aggressive perennial weeds, possess the resilience to push through the fabric over time, undermining the barrier.
After clearing the vegetation, the soil surface must be smoothed out, removing any large clumps, rocks, sticks, or construction debris. Sharp objects left on the ground can easily puncture the material when pressure is applied, such as from walking or placing heavy mulch. A flat surface also prevents the decorative top layer, like gravel or mulch, from sliding off the slick fabric surface, particularly on slight inclines.
This is the only opportunity to amend the soil with compost or fertilizer, as the fabric will act as a permanent barrier against future organic matter from the surface. Any necessary adjustments to existing irrigation lines, such as drip systems, should also be completed at this stage. Once the area is clear, smooth, and amended, the soil is ready to receive the fabric.
Securing and Finishing the Installation
With the ground prepared, the fabric should be unrolled and carefully cut to fit the designated area, ensuring a clean fit around any existing plants. When covering an area wider than the fabric roll, multiple pieces must be overlapped to prevent weeds from growing through the seams. A minimum overlap of six inches, and ideally up to twelve inches, is necessary to create a sufficient barrier against light and weed emergence.
The fabric is then secured to the ground using specialized U-shaped landscape fabric staples or pins, typically made of galvanized steel. These staples should be inserted every three to five feet along the edges and seams to hold the material taut and prevent wind or shifting soil from displacing it. For areas with high foot traffic or on slopes, the pins should be placed closer together, sometimes as frequently as every foot, to provide maximum stability.
Finally, the entire surface of the landscape fabric must be covered with a layer of mulch, gravel, or stone, which serves a dual purpose. The covering provides the weight needed to keep the barrier firmly against the soil and shields the fabric from direct UV light exposure. Even UV-resistant fabrics will degrade faster when left uncovered, and a three-inch layer of decorative material will significantly extend the lifespan of the installation.