Answer: An organic mulch such as shredded bark or chopped rotted leaves or cocoa bean shells, etc. is preferred for one primary reason: an organic mulch will eventually break down and help feed the soil, an important ongoing benefit that rocks do not offer. A rock mulch will also reflect heat, and in a warm climate this can be harmful to the shrubs (azaleas are particularly sensitive) during midsummer, while an organic mulch is cooler. Rocks will work down into the soil during seasonal freeze thaw cycles so it is a good idea to use an air and water permeable weed fabric type barrier beneath the rocks. This will keep them from disappearing into the soil and will make it easier to remove them if anyone ever wants to. It will also go a long way toward preventing weed growth -- the rocks are a perfect weed seed bed. For this reason it should be raked and weeded occasionally. An organic mulch can also be raked occasionally and will need to be replenished from time to time.
Q&A Library Searching Tips