Some of the best results have been obtained when using a combination of landscape fabric covered with an organic material. As the mulch decomposes it can produce a layer of soil in which weeds can grow. Using a coarse-textured mulch material, such as pine bark nuggets, will delay the development of this layer. Black plastic is not recommended as a mulch for trees or shrubs. It prevents normal water, fertilizer, and air and gas movement.
Plants tend to become shallow-rooted and subject to winter injury.
Mulch can be applied any time of the year, although the best time is late spring after the soil has warmed. Early spring application will delay soil warming and possible plant growth. For beds mulch the entire area. For individual plants, such as trees, mulch an area of 2 feet for each inch of trunk diameter. On previously mulched areas, apply a 1-inch layer of new material.