Landscape fabrics are thin barriers covered with tiny holes. They are typically made of plastic, but may also be made of burlap, other natural fibers, or recycled plastics. They are effective at blocking weed growth while allowing water and air into the soil. They should be used in conjunction with thick, effective mulch.
“As a garden mulch, fabrics do provide good early-season weed protection. However, because fabrics allow some light to penetrate, weeds will germinate below and break through the cover unless some other material, such as rocks or bark mulch, are placed on top,” Lerner said.
According to Dr. Andrew Senesac of the Long Island Research Laboratory, landscape fabric will block many weeds, but it also limits some desirable flower production by restricting the spread of shoots, and inhibits the spread of some groundcovers and other spreading plants.
Some particularly hardy weeds and grasses can even germinate with no soil on top of porous weed barriers, then force their roots down.