Does Hardwood Mulch Repel Ants?

Ant Issues

• Ants aerate the soil, eat caterpillars, fleas and termites and assist with the decomposition of animal remains. Without ants, dead moles and rodents would take longer to become fertilizer in the soil. One of their most troublesome habits for the gardener is their helper role with honeydew producers -- pests such as aphids, mealy bugs and whiteflies. The honeydew attracts ants, and ants may nest near the honeydew producers, helping drive away predators, according to the University of California Integrated Pest Management program. Ants may also invade your home, and carpenter ants can cause damage to wooden structures.

Ant-Repelling Mulch

• For an ant-repelling mulch, choose cypress or cedar. Cypress, although a conifer, is a deciduous tree that has more in common with hardwoods than with other softwoods. It repels ants, although it may not be effective on all species. Cedar, a softwood, is made from the same aromatic tree that repels moths that eat clothing. Cedar mulch deters odorous house ants and Argentine ants, according to the University of Washington Extension. Eastern redcedar mulch (Juniperus virginiana), in particular, effectively deters ant colonization, according to the United States Department of Agriculture Forest Service website. This variety of cedar has a high proportion of heartwood, which makes it rich in the pungent oils that repel ants.

Mulch Guidelines

• If you use wood mulch, including cedar or cypress, keep it at least 6 inches away from buildings. Any wood mulch makes the underlying soil more ant-friendly. Limit the mulch to 2 to 3 inches deep. A deeper layer of mulch may encourage carpenter ants to nest, according to the University of California at Davis Integrated Pest Management Program's website. An invasive ant species, the dark rover ant (Brachymyrmex patagonicus Mayr), will nest in hardwood mulch, according to the Mississippi Entomological Museum. If you have problems with ant nests near your house, or live in an area with problem ant infestations, a dry mulch such as gravel or lava rock might be the best choice.

Dry Mulch Alternative

• To keep ants out of the house, in addition to patching any cracks or damage to the foundation, surround the house with stones or gravel in a plant-free zone, the University of California at Davis Integrated Pest Management Program suggests. Keeping a dry area around the house reduces the moisture ants require. Wood mulches can supply the right conditions for ant nests by holding water and decomposing. Cut back plants and trees that touch the house. In addition to being sources of moisture, they serve ants as handy ladders for finding ways into your home.