Weed barriers do not promise weed-free gardens; gardeners who install weed barriers hope for them. All weed barrier materials, from the original poly "landscape cloth" to modern geotextiles to organic sheet barriers, have their benefits and drawbacks. Before you decide to install one in your garden or orchard, decide what you hope to accomplish, how much you’re willing to spend and how much effort you are willing to put in maintaining that barrier that is supposed to save so much work.
Thoroughly cultivate the area to be covered and add compost to lighten and enrich the soil. You won’t have another chance for several years. Remove weeds as you go. Complete this task several days before you plan to install the barrier and repeat it before laying the cloth.
Apply a layer of compost or manure to separate the topsoil and the cloth. This layer will also encourage biological activity in the soil underneath the cloth.
Lay the fabric down on the area, taking care not to overlap edges of pieces. Bring edges together and insert pins to hold the pieces together. Place pins (which look like big staples) in the cloth every few feet to hold it down.
Mark plant locations with a white or light-colored grease pencil and make “X”-shaped cuts where plants will be located. If perennials, shrubs or trees already are growing in the plot, make your cuts before laying the fabric and slide it down over the plants.
Plant in the “X” openings, then cover the fabric with an inch or two of organic mulch. Wood chips, compost or other organics are lighter than stones and will compact soil less quickly. They will also hold moisture, keeping rain from running off of the fabric before water can percolate through the fabric.
Organic Sheet Barriers
Cut or flatten--do not remove--weeds on the surface you will cover. Sheet barriers mimic the natural processes on the forest floor where everything is used.
Break apart cardboard boxes and remove metal fasteners that may pose a hazard to hands or feet. Lay the cardboard over the weeds, overlapping so that no light can get through to the ground--and weeds--underneath.
Water the cardboard well to start the decomposition and keep it in place. If you run out of cardboard, use newspaper or any non-laminated paper with soy ink to finish.
Top the cardboard with an 8 to 10 inch mulch layer of wood chips, grass clippings, straw or other material. Some of this layer can also be well-rotted compost but it must all be weed-free. When it sinks down to a layer that is 3 to 5 inches thick, the weeds will be gone for good and the plot full of good garden loam, ready to plant.
Plant your garden or other landscaping and mulch again to keep weeds from reappearing.