Mulch is an indispensable element to cultivate a healthy and lively yard over the long-term. It is an organic material that is scattered around the plants as a way of protecting the soil. The cover retains moisture and nutrients in the ground through insulation. Normally you should spread on an inch or two of fine mulch around your plants as more than two inches of it may stifle the plants. However, if the mulch you use is bristly, such as shredded bark, then three or four inches may be appropriate.