Landscape mulches are an important component of sustainable gardening, according to Washington State University. The right mulch will help contribute to the overall health of trees and shrubs by choking out weeds that can compete for water and nutrients in the soil. Mulches also help improve the soil by increasing water retention and reducing erosion. Wood chips are one of the most popular forms of mulch available for landscaping today because their non-uniform edges resist compacting and promote colonization by healthy soil microbes. You can find wood chips in bags at many garden centers.
Time wood chip mulch application for winter or early spring before weeds become established. Mulch that is applied in a thick layer over the soil prevents light from reaching weed seeds and helping them to germinate. It also creates a hostile environment for weed runners to prevent spreading weeds from creeping into landscaped areas.
Apply a thin layer of compost beneath the mulch. This compost layer creates what landscapers call a mulch sandwich that mimics natural mulches found on a forest floor. The nitrogen-rich compost layer helps to add nutrients into the soil and nurture plants.
Spread wood chips over the landscaping area in a 4- to 6-inch layer. This creates a layer of mulch that is thick enough that weeds have trouble becoming established.
Rake mulch away from the trunks of trees and shrubs. When you pile mulch over the trunk of a tree or shrub, landscapers call it the volcano effect. The mounded wood chips create a moist, low-oxygen environment that is perfect for fungus to grow in. This fungus can infect trees and cause them to decline.
Replace wood chips as they decompose on the bottom of the wood chip pile. Try to keep the layer of wood chips between 4 and 6 inches over the soil.