Question: As a result of the storm I have a large pile of woodchips from all the cut down trees. Can I use these in my flower and vegetable beds as mulch?
Answer: Mulches have come to be recognized as essential components of gardens and landscapes. They enhance the beauty, reduce weed growth, retain soil moisture and prevent erosion and compaction. Depending on the composition and how they are used they can also create problems by fostering nuisance fungi, harboring insect pests and depleting soil nitrogen. Many problems can be avoided with some simple precautions.
Tree bark has been the most popular mulch material. According to Dr. Joseph Heckman, Ph.D., a professor of Soil Science at Rutgers University where he teaches courses in soil fertility, wood chips can contribute to the formation of a more persistent soil organic matter. It is rich in lignin, and other organic molecules that are resistant to decay and will improve soil quality. When the mulch material comes from trees in early summer there is additional leafy material that has a high nitrogen content. The smaller particles will decompose quickly while the larger ones may take two or more years to completely decompose. As a soil amendment wood mulch is also a good source of potassium.
Some of the concerns regarding mulch application have been disproven when put to the test in research trials. Mulches were blamed for acidifying soils. Field tests have shown there is a transient change in ph in the decomposing layer but not in the underlying soil. An application of wood mulch may temporarily increase the need for nitrogen fertilizer. The zone of nitrogen deficiency is at the mulch soil interface, and plants with well-established deep roots should not be affected. Therefore it is not advisable to put fresh wood chips on annual or vegetable beds.
Before installing wood chips apply a thin layer of a more nutrient-rich mulch such as compost. This mimics what is naturally occurring on a forest floor. It is not required but may help with nutrient deficiencies. Your mulch should be applied at a rate of 4 to 6 inches in ornamental plantings of trees and shrubs or at a depth of 8 to 12 inches for restoration sites for complete weed suppression. When applying mulch keep the mulch at least six inches away from the trunks of woody plants. Trunks encircled with mulch stay moist and can be harmful and favor infections from pathogens.
Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Extension, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email: