Mulches for the Landscape

ature mulches plants with fallen leaves and other organic materials. Mulching, as practiced by gardeners, is merely an adaptation of this natural process.

Advantages of Mulching

Mulching offers several advantages, the greatest being conservation of soil moisture. Evaporation of water is greatly reduced when the soil is protected from the direct rays of the sun and moving air. Also, rain falling on the mulch does not pack the soil surface the way that rain falling on bare soil does. Mulch also decreases erosion.

Another important advantage of a mulch is the control of weeds. Mulch greatly reduces the need for weeding, and if used with a preemergence herbicide, which kills weeds before germination, the benefit will be even greater. It is especially important to mulch rather than cultivate around shallow-rooted plants such as rhododendrons, azaleas, and camellias.

Controlling soil temperature is another plus with mulch. Lower and more uniform soil temperatures in summer favor root growth and beneficial bacterial activity in the soil. High summer temperatures may injure these microorganisms as well as the roots near the surface of the soil. In winter, frost penetration is less likely to occur in a mulched area. Evergreens must absorb moisture in the winter as well as summer; therefore, a winter mulch can prevent the soil water from freezing and becoming unavailable to plants.

Organic matter used as a mulch can improve soil structure and tilth. As it decays the mulch material works down into the topsoil. Decaying mulch also adds nutrients to the soil.

Mulching material, such as pine bark or pine needles, improves the appearance of the garden. It is valuable for covering beds near the house or in areas where neatness is important.

Disadvantages of Mulching

There are a few disadvantages to mulching. First, the cost of some materials can be a drawback to large-scale mulching. Also, some mulches are not readily available.

When using sawdust and wood chips as a mulch, nitrogen starvation sometimes occurs, but this is easily corrected by using additional nitrogen.

Heavy mulching over a period of years may result in a buildup of soil over the crown area of the plants. This condition is especially harmful to camellias. After 3 years, it may be advisable to rake off the old mulch before applying a new layer to prevent plant roots from developing in the mulch material.

**MULCHING MATERIALS**
Material	Depth to Apply	Remarks

Rotted Manure	1 to 2 inches	May contain weed seeds. Should be well composted to prevent burning plants.

Sawdust Wood Chips Wood Shavings	1 to 2 inches 2 to 3 inches 2 to 3 inches	Low in plant nutrients. Decomposes slowly. Tends to pack down. Well-rotted materials preferred. Can be fresh if ammonium nitrate is supplemented at the rate of 1 pound per 100 square feet. Keep away from building foundations; can attract termites.

Ground Corn Cobs	2 to 3 inches	Excellent for improving soil structure.

Pine Needles	3 to 6 inches	Will not mat down. Fairly durable. Great for winter protection on perennials.

Peanut Hulls	2 to 3 inches	Supplies plant nutrients and improves soil structure. Fairly durable. May contain nematodes.

Whole Tree Leaves Shredded Tree Leaves	3 to 6 inches 2 to 3 inches	Excellent source of humus. Rots rapidly. Relatively high in nutrients. Oak leaves especially valuable for azaleas, camellias and rhododendrons.

Hay Grass Clippings	3 to 6 inches 1 to 2 inches	Unattractive but readily available. Grass clippings tend to mat and can repel water if they dry out. Should not be applied deeper than 2 inches.

Hay Straw	6 inches	Same as above, but lower in nutrients although furnishes considerable potassium.

Pecan Hulls	1 to 2 inches	Extremely durable. Availability limited. Will stain concrete.

Gravel Stone Chips	1 to 2 inches 1 to 2 inches	Limited use but particularly good for rock garden plantings. Extremely durable; holds down weeds but does not supply plant nutrients or humus.

Newspaper	½ to 1 inch	Good in open woodland, particularly under pines, to control weed growth. Should be covered with another mulch to improve appearance and prevent scattering.

Bark	2 to 3 inches	Ground and packaged commercially. Especially attractive in this form.

Kerry Smith, Extension Home Grounds Program Coordinator. Originally prepared by J. David Williams, Extension Horticulturist, Associate Professor, Horticulture, Auburn University, and Ronald L. Shumack, former Extension Horticulturist.

For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.

If you have problems loading this document, please email publications@aces.edu for assistance.

Publications Homepage | ACES Homepage