Will Perennials Spread With a Weed Barrier?

Reduced Growth

• How well perennials spread in a bed covered with weed barrier depends in part on the strength of the fabric and the strength of the plants. Strong vigorous plants are more likely to spread than small, fragile plants. Heavyweight weed barriers reduce growth more than lightweight inexpensive products. In general, though, weed barriers do inhibit the growth of perennials in the flower garden.

Other Potential Drawbacks

• In addition to limiting perennials' growth, weeds eventually grow through weed barriers. The roots become entangled in the fabric, making them more difficult to remove than if the soil was bare or mulched with an organic material. Weed barriers eventually decompose, requiring replacement. As mulches thin, weed barriers become visible and have an unattractive, messy appearance.

Solutions

• Cutting larger holes in weed barriers allows perennials to spread but may also allow weeds to infiltrate. Another option is to select compact perennials or grow annuals instead. Select a lightweight weed barrier and secure it in place with landscaping pins.

Bottom Line

• Eliminate weed barriers in perennial beds and apply a 3 inch layer of wood chip mulch instead. The mulch inhibits most weed growth, while allowing perennials to spread. Any weeds that appear are easily removed by hand weeding. Wood chip mulches also add organic matter to the soil as they break down. Save weed barriers for vegetable gardens or permanent beds with shrubs and trees only. Cover the weed barrier with rock or gravel, rather than wood chips.