Principle No. 6

Mulches cover the soil and are used to minimize evaporation, reduce weed growth, cool the root zone and slow erosion. Mulches can also give beds a finished look, increasing a garden’s visual appeal. Apply bark mulch directly to the soil surface or rock mulch over a landscape fabric.

• Organic mulches, such as bark chips, pole peelings or wood shavings should be applied in a layer 4 inches deep. Organic mulches decompose and improve soil texture, but they must be replenished periodically. 
• Other mulches such as rocks or gravel should be applied in a 2 inch layer. They rarely need replacement and are good in windy spots. Rock mulch can increase heat to the soil which not all plants can tolerate.
• Landscape fabric is an option to reduce weeding. Don’t use black plastic in areas that have plants; it prevents air and water from reaching plant roots. Many xeric designs do not use landscape fabric as the spreading of plants is desired to provide a full, filled-in look. Also, bark mulch will stay in place better when not placed on fabric.