Historically speaking, bark mulch is the most common type of mulch available to the homeowner and gardener. You can go to about any nursery, hardware store, or home & garden center and find either bulk or bagged bark mulch for sale. The problem for the consumer is deciding what type of bark mulch is best for the intended use of the product. Bark mulches commonly available in our immediate area are classed into three basic types for decorative and functional mulches: hardwood, pine, and cypress. These are byproducts of logging, lumber, and paper industries, and each differs in appearance and quality as well as having certain advantages and disadvantages.
Hardwood mulch consists of shredded bark from hardwood trees. This is a by product of the debarking of logs by the lumber industry. The hardwood bark mulch can be fresh or composted product. Fresh hardwood bark mulch is coarse in texture and lighter in color and can readily become sour or acidic mulch that could cause marginal leaf chlorosis, scorch, and plant death. The composted hardwood bark mulch has been aged for 6 to 9 months and is less acidic, finer in texture, and darker in color. The composted hardwood mulch is the most common mulch in use today, fairly inexpensive, and the most readily available. It can be alkaline, but this can be managed by adding elemental sulfur. Properly composted hardwood bark mulch is rich in nutrients, attractive in appearance, and can provide insulating properties to plants. The disadvantages of aged hardwood mulch are an attractive environment to insects, fast decay because of high cellulose content, fine texture with the risk of oxygen depletion of the soil, compaction which can increase chance of fungus or disease, and the dark color in the summertime can increase soil temperature to well over 120 degrees Fahrenheit.
Pine mulch is bark from pine trees of the eastern and southern states and, less commonly, some western species. It is also a by product of the pulp and paper industry and lumber industry. This is a mulch that can range in size from 2 inches to a very fine texture and has a very attractive reddish brown color. The advantages of pine bark mulch are decay resistance, excellent soil conditioner, and because of its acidity, it promotes root growth for acid loving plants. Pine mulch has a disadvantage of being easily displaced by water, can have some negative effects on soil pH, and can attract some types of insects.
Cypress bark mulch is the most expensive and best quality of the bark mulches. It is found in two grades: grade A is bark only and the highest quality, and grade B+, which is the whole tree and bark shredded as mulch. It can range from reddish brown to light tan in color. Cypress mulch comes from the swamps of Southern Georgia and Florida. The advantages of cypress bark mulch are very decay resistant, very long life mulch, very insect resistant, and aesthetically pleasing. The disadvantages of cypress are expense and the fact that cypress wood fiber will not decay in soil, which can interfere with the soil water holding capacity.
In addition to natural color fiber we have many dyed wood fiber mulches. Most of these mulch types are a recycled wood fiber that has a mineral dye add to enhance the color fastness. This serves to maintain color on these mulches for a longer period of time as compared to natural fiber mulch. Most common colors are red, black, and brown.
In review, the ideal mulch is economical, readily available, easily applied and removed, stays in place well, and supplies organic matter to the soil, yet is free of noxious weeds, insects, and disease. It should also provide three very important functions: suppress weeds, conserve moisture, and moderate soil temperature.