Amy Smart, Conservation Specialist
Utilizing mulch throughout your property improves aesthetic quality and reduces tedious maintenance requirements. The many additional environmental benefits mulch provides can assist you in managing for the health of your landscape. Mulch can improve the health of your soil, support vigorous plant growth and supply wildlife habitat while decreasing irrigation water requirements and suppressing weeds. Understanding these positive functions can help you determine the best type of material to apply to your landscape based on your particular goals.
Are you experiencing erosion on your property? Is maintenance an issue? Do you have to water plants in a certain area more than you would like? Would you like to improve the health of your soil? There are many varieties of organic and in-organic mulch that can alleviate these problems by providing different benefits. Some examples include:
Alfalfa Shredded Bark Cocoa Hulls
Straw Wood Chips Rocks
Dried Grass Clippings Newspaper Glass
Organic mulches improve the quality of your soil by allowing better water infiltration and retention and increasing plant essential nutrients. Healthier soils promote microorganisms that help lessen soil compaction and improves soil structure. Organic mulch can help promote the establishment of vegetative cover to further decrease erosion on bare slopes. Both organic and in-organic mulch can help control soil erosion by providing protection from water and wind. Covering soil with mulch moderates soil temperature extremes that can reduce the need for irrigation in summer months and protect plants from frost through winter. Evaporation rates are less when mulch is applied, cutting the need to water plants by as much as 50%. Not only does this save water but energy use associated with irrigation is diminished saving even more resources.
By improving the quality of soil, plant vigor and wildlife habitat is improved as well. Some mulches creates a favorable environment for earthworms that continue to improve soil health. Mulching may also provide habitat for beneficial insects and provide pest suppression. When applied at the proper thickness, mulch keeps weeds down decreasing the need for maintenance. Weeds that do grow are much easier to pull when mulch is applied. Once the goal for your project is identified, it’s easier to select the type of mulch that provides the greatest impact based on your needs.
Mulching with straw is useful on bare slopes experiencing erosion. Not all straw is weed free however so it is important to purchase straw that does not carry seeds from invasive species. If establishing vegetation is the goal, native seeds benefit from a layer of straw mulch as it protects the soil surface from erosion, holds moisture and moderates soil temperature. Straw mulch should be applied at a rate to achieve a minimum 70 percent ground cover to help reduce erosion and allow sunlight and air movement for vegetation to grow.
Dried grass clippings can also be applied in this scenario and are a good choice in vegetable and annual flower beds that receive annual cultivation. This type of mulch recycles its nutrients into the garden bed relatively quickly. Grass clippings make good mulch when applied in thin layers and allowed to dry between applications.
Wood chip mulch is great around trees, shrubs and perennials. Be sure to keep mulch at least 6 inches away from the base of trees and shrubs. Replacing grass under trees with mulch can minimize competition for water and nutrients. Mulching materials that mesh together are more effective at reducing water evaporation from the soil. Wood chips are not recommended where the soil is routinely cultivated to prepare a seedbed, such as in vegetable or annual flowerbeds.
Newspapers are printed with soy-based inks and are safe for use as an underlay for wood chips or grass mulch. The newspaper shuts out light, giving a quick stop to germinating weed seeds. Apply newspapers only one to two sheets thick and top with wood chips or grass to hold it in place. Any remaining newspaper at the end of the growing season may be cultivated into the soil in the fall.
Rock over landscape fabric is the preferred material for non-plant areas and often considered as low maintenance. Rock mulch has the advantage over other mulch in that it does not blow, float, or decompose. Using rock in succulent gardens is a common practice. However, in planting beds, rock mulch increases temperatures and may increase water requirements.
In general, you can save money by purchasing mulch in bulk. Bulk mulch is measured in cubic yards. You can calculate the volume of mulch you need by multiplying the area (in square feet) by the depth (fraction of foot, not inches), then dividing by 27. Before applying mulch, remove weeds and water thoroughly. The desired depth of mulch depends on the type and chip size. Smaller size chips should not exceed a one to two inch depth. Larger chips are typically applied at three to four inches deep. Remember that additional mulch needs to be added every few years to bring the mulch depth back to the desired amount.
Whether you want to improve curb appeal, decrease weeds, add to the health of your soil or reduce irrigation water, mulch is a great tool to incorporate into your landscape. Determine your goals and select the right mulch for you!