Customers often request to have landscape fabric installed under mulch to help prevent weeds. This is not an acceptable industry weed prevention method for mulch beds.
Mulch is a wood product that will deteriorate and decompose. As that happens it turns into nutrients for the plant material. Nutrients cannot break down into the soil if you have the landscape fabric under the mulch. This will create fungus and weeds on top of the fabric. At Squeals Landscaping Inc. we recommend Preen to help reduce the germination of weeds.
Landscape fabric is designed for use under decorative stone. The fabric will let air, sunlight, and water get into the ground but will prevent weed growth in the landscape stone beds. Since landscape stone will not deteriorate and decompose like mulch, the ground chemistry will not have an impact.
Never use plastic under mulch or decorative landscape stone. This prevents air, water and sunlight ground penetration; which becomes an ideal environment for plantings to fail.
In conclusion, when using decorative landscape stone in beds then use landscape fabric to prevent weed growth. When using mulch skip the fabric and use Preen for weed prevention!