Soil should be amended to bring the pH and soluble salts to an optimal level. Mulch Mulches discourage weeds from growing, conserve moisture during drought periods, allow better use of water by controlling runoff, and increase the water-holding capacity of light sandy soils. Mulches help maintain a uniform soil temperature. Many organic materials can be used as mulch. In North Carolina, pine needles, pine bark, compost, peat moss, and decayed sawdust are used frequently.
Most landscape plants benefit from having organic matter worked into the root-zone area.
Mulch can be applied just about any time of the year when trees and shrubs are being planted. If applied earlier, the mulch will keep the soil temperature lower and may delay root growth. Mulches should be applied 3 to 4 inches deep over relatively clean, weed-free soils. Do not make the mistake of simply covering bermudagrass, nutgrass or other perennial garden weeds with a layer of mulch. Weeds should be identified and eradicated before the mulch is applied.