Mulch is any material places over the soil to control the growth of weeds, keep the soil cool, and conserve moisture. An essential part of any landscape, right? Not necessarily!
Gardeners do have options when it comes to mulch. Light cultivation or tilling of the soil is highly effective in controlling weeds and conserving moisture. Just ask any farmer and you'll learn how effective it is. However, it is a time consuming, high maintenance process most homeowners choose not to use. This accounts for the high popularity of both organic and inorganic mulches in today's landscape. Let's look at both options in detail.
Organic Mulches: This category includes item such as chopped leaves, compost, cocoa/rice hulls, and shredded bark. It basically includes anything that once was alive. Organic mulches are by far the most beneficial to your landscape. A 2" layer around perennials and up to a 4" layer around trees and shrubs will effectively cool the soil white controlling most weeds. Yes, you will have to add fresh mulch every few years to maintain the proper depth. Adequate layers of organic mulch require no man-made weed barriers and help add organic matter to our soils as the decompose. One very important point that must be remembered is to NEVER pile mulch up against the trunks of trees or the crowns of shrubs and perennials. "Volcano Mulching," as it has been nicknamed, invites rot and the invasion of insects to the growing points of our plants.
Inorganic Mulches: This category includes decorative stone, rubber, and plastic sheeting. Inorganic mulches are basically maintenance-free once installed and require the use of weed barrier fabrics. They can often increase soil temperatures in full sun and may limit the movement of moisture and oxygen through the soil. Price will vary greatly depending on the exact choice as well as shipping and delivery pricing. Stone should be installed to a depth of 2" and once again not piled up against the trunks and crowns of trees and shrubs. Many perennials will not survive in an inorganic mulch environment.
Ultimately, the choice of utilizing organic vs inorganic mulches is yours. However, the decision must be based on the level of maintenance you desire AND the requirements of the plants you have chosen to grow. A beautiful grouping of massed perennials will cry out for organic mulches while simple plantings of trees and shrubs will do just fine when mulched with inorganic materials. The choice is ultimately yours so choose wisely.
