2 inches of mulch naturally retains moisture, offers a neat appearance and greatly reduces the amount of weeding. Keep mulch a couple of inches away from the base of trees.  Freshen your mulch with a quick cultivation once or twice a year.  There are several varieties available, from Cedar to Cocoa bean, Wood Chips, Bark etc. do NOT use dyed wood mulch, it can cause problems if they are chemical based dyes that leach and injure sensitive root systems. Learn more.