In fact, research has shown that trees and shrubs with landscape fabrics around them grow just as well as ones without fabric, yet without the same weed competition. Appleton has been testing various brands of landscape fabrics since 1987. When planting and transplanting annual flowers, gardeners tend to make many holes, opening the fabric to weed invasion. And most perennial flowers don't expand and fill in properly when grown with landscape fabrics. Also, don't get high expectations that these fabrics will control all weeds, says Appleton.
Landscape fabrics control annual weeds better than perennials.
When installing landscape fabrics, first clear the area of all existing weeds. Anchor the fabric with metal pins with at least a six-inch overlap between pieces. Then cover it with mulch, if desired. Our research has shown that no more than a one-inch depth of organic mulch, such as shredded bark chips, is recommended over the fabric. Organic mulch applied any deeper allows weed seeds to germinate easily in the mulch.