It decomposes relatively slowly, and it is very attractive. This material contains bark and pieces of wood of various sizes and makes an attractive mulch. Small wood chips decompose very rapidly using nitrogen from the soil, which needs to be replaced by nitrogen fertilizer. Wood chips may attract termites and other insects. Pecan Shells Pecan shells make a long-lasting, attractive, dark brown mulch that is effective in retaining moisture in the soil.
Availability is limited to areas where pecans are processed.
Ground Cover Many perennial ground cover plants, such as ivy, periwinkle, pachysandra, mondo grass and liriope, will cover the soil and act as a mulch. For more information on groundcovers, refer to HGIC 1100, Groundcovers . These materials are permanent and are best used for permanent plantings such as foundation plants. A 1- inch layer of small rocks will provide good weed control. Do not use them around acid-loving plants since the rocks may add alkaline elements and minerals to the soil.