As with grass clippings around plants, keep mulch away from plant stems and only use a three to four inch deep layer. Mulch piled against plant stems holds moisture around the stems and can lead to decay.
Too deep of a mulch layer reduces oxygen exchange between air and soil. Keep in mind that roots need equal amounts of oxygen and water. This is why overwatering is harmful to plants and why soils should be kept moist but not saturated. And many should be allowed to dry briefly between irrigation.
Inorganic mulch, like rock, is often used and placed on a weed mat. While this is a common practice, know that it reduces oxygen…
