Landscape mulches are recognized as pivotal components of environmentally sustainable green spaces.
Select the right mulch and you reap the benefits of healthier soils and plants. Choose the wrong mulch and the only plants that thrive are the weeds.
The philosophy behind landscape horticulture is the long term, sustainable management of a system.
An excellent choice is arborist wood chips for an all-around landscape mulch.
In areas where trees are a dominant feature of the landscape, arborist wood chips represent one of the best mulch choices for trees and shrubs. Wood chips are one of the best performers in terms of moisture retention, temperature moderation, weed control, and sustainability. In many urban areas, arborist wood chips are available for free, so are economical and practical.
Unlike the uniform nature of sawdust and bark mulches, wood chips include bark, wood and often leaves. The chemical and physical diversity of these materials resists the tendency towards compaction seen in sawdust and bark.
Additionally, the materials vary in their size and decomposition rate, creating an environment that is subsequently colonized by a diverse soil biota. Plus, attractive wood chips are as a mulch. Natural, and unique, and perfect for many settings and garden styles!
Wood chips are considered to be slow decomposers. Wood chips supply nutrients slowly to the system; at the same time, they absorb significant amounts of water that is slowly released to the soil. Wood chips have been cited as superior mulches for enhanced plant productivity.
Arborist wood chips provide incredible weed control in ornamental landscapes. While there are imported wood chips for sale, locally produced wood chips are often free. In a society where using locally produced materials is increasingly popular as a measure of sustainability, arborist wood chips are a natural choice.
Enjoy the smell of fresh wood chips while spreading them out over the landscape. Some of the nutrient value (particularly nitrogen if the chips contain leaves or needles) will be lost if the wood chips are aged.
Begin mulch application before annual weeds are established. Mulch is most effective in suppressing weeds when weeds are not yet present on site. Bare soil should be mulched as soon as practical, especially in the spring and fall when weed seed germination is at its peak.
If this is not possible, the most effective, non-chemical way to remove weeds prior to mulching is to mow them as close to the ground as possible, followed immediately by mulching.
Prune or mow perennial weeds at the root crown in early spring when root resources are lowest (generally just as leaf growth begins). Then pull re-sprouting perennial weeds covered in mulch; the mulch layer prevents erosion and facilitates pulling. Remove all noxious weed materials from the site to prevent re-rooting or seeding.
A successful wood chip mulching must be deep enough to suppress weeds and promote healthy soils and plants. Shallow mulch layers will promote weed growth and/or require additional weed control measures. Apply 4-6 inches for ornamental sites and 8-12 inches for restoration sites and/or perennial weed problems.
Keep mulch away from trunks of trees and shrubs. Piling mulch against the trunks of shrubs and trees creates a dark, moist, low oxygen environment to which above-ground tissues are not adapted. Rather than creating mulch volcanoes, instead taper the mulch down to nearly nothing as you approach the trunk.
This donut-shaped application will protect the soil environment as well as the above-ground plant tissues.
Replace mulch as needed to maintain desired depth; replacement rate will depend on decomposition rate. Once mulch is applied, little management needs to be done other than reapplication to maintain minimum depth.
Elaine Webber is a Clallam County Master Gardener.