Mulching isn't a new idea. Leaves, pine needles and decaying wood chips have mulched natural settings for thousands of years, but recently, man-made and installed mulches have become big business. Mulches provide many benefits. Weeding is reduced by as much as two-thirds, according to Cornell University, while moisture levels in beds is doubled. Mulches also reduce soil compaction and erosion and regulate soil temperatures. For many gardeners, the benefits of mulches outweigh the initial costs.
Many mulches are available that are the natural by-products of industrial processing. Wood chips and cocoa hulls are two examples. Other popular mulches include salt hay, straw, gravel, wood bark, landscaping fabric, compost and rock. Costs vary considerably depending on the materials chosen. Some mulches, such as cocoa hulls, are only available in regions that process those materials.
Mulches are generally most expensive when purchased in bags at local nurseries or garden centers. These mulches are appropriate for small landscaping jobs. For mulching larger areas, buying mulches in bulk through a landscaping firm is the most economical choice. Some communities offer free wood chip mulch as a by-product of tree trimming. Typically, residents dig and haul the mulch themselves. A compost pile offers a readily available supply of free mulch.
When considering the cost of a mulch, consider the long-term durability. Gravel is one of the most costly mulches to install, but it lasts virtually forever. Other mulches, such as cocoa hulls, straw and wood chips break down over time and require replacement. Over the course of several years, replacement costs for less expensive mulches may equal that of more permanent products such as gravel or rock.
Economic costs aren't the only considerations when choosing a mulch. All mulches have potential positive and negative attributes, including how they impact the soil. Fresh wood chips, for example, may initially take nitrogen from the soil as they decompose, making it less available to plants. Some types may even leach harmful chemicals. As natural materials break down they improve the soil's texture. Gravel stays put and doesn't rob the soil of nitrogen, but it is more difficult to remove and it retains heat in the summer. Also, it doesn't improve the soil. Landscaping fabrics work well when installed under permanent beds covered with gravel. They may slowly work their way up when placed under lightweight mulches.
There is no one ideal mulch, but the best mulches have a few common attributes. A good mulch, according to Cornell University, should be economical, easy to install, readily available and stay in place. Ideally, it should also add organic material to the soil and be pest and disease free.