Garden Column for the Salisbury Post
Darrell Blackwelder
January 24, 2003

    I’ve had my eye on the mountain of ground storm debris at the fairgrounds since the county began grinding a few weeks ago. The once huge mounds are now no more than large hills as many have hauled away the ground debris to use as mulch in landscaping projects around their homes.

Some have contacted me inquiring about using this mulch, concerned that its use could cause problems, especially with insects. Any mulching material containing green wood or cellulose is going to attract termites and other insects. Termites feed on the cellulose in green or un-decomposed wood fibers. Those concerned about green mulch attracting termites may choose not to use this mulch near the foundation of their home or other structure.

Freshly ground mulch is excellent for mulching garden paths and hiking trails. Tree and vegetative material fibers lock together, both physically and by microbial action forming a mat which allowing water to penetrate to the soil. These fibers stay in place and do not float off in a hard rain as pine bark chunks or hardwood barks. For this reason, freshly ground mulch is especially useful for erosion control as silt screens filtering water runoff.

Many want to use the mulch as soon as possible around trees or shrubs. I discourage the use of fresh wood chips or ground limbs around trees and shrubs. Decomposing wood depletes nitrogen from the soil, especially if the chips are worked into the soil. Bacteria used in the natural decomposition process take away nitrogen, which is essential for plant growth and development. The end results are shrubs that are yellow and anemic from lack of nitrogen.

Many have also complained that the sap from freshly ground oak limbs and twigs damages shrubs. I recommend ground storm debris be allowed to compost or rot for a few months or years if possible before use around shrubs, especially if you plan to work the material into the soil.

The other concern is that this mulch is not a homogeneous mixture. A load of ground mulch is sure to contain ground Bradford pear limbs along with any other combination of pine, oak, pecan, etc. Various tree species such as black walnut and sycamore inhibits plant growth or certain trees and shrubs stunting and delaying normal growth.

    Hats off to the county for grinding storm debris into mulch and offering it to the general public. This is both a smart and environmentally friendly method of dealing with this problem. However, those that want to use the material as mulch should strongly consider composting before use near foundations and around valuable landscape plant materials.

Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com or e mail Darrell_blackwelder@ncsu.edu or phone at 704-633-0571.