Year Round Gardening: The Importance of Mulch to Colorado Soil Way of life
When planting perennials, shrubs, trees and vegetables, it is important to mulch the surface of the soil.
Mulch is a material that sits on the ground while a soil amendment is mixed into the soil. It retains moisture in the soil, prevents water runoff, moderates soil temperature, prevents soil compaction, inhibits weed growth, and gives a finished look to a landscape.
Mulch comes in many forms: grass clippings, wood and bark chips, gravel, composted leaves, straw and pine needles, to name a few. When selecting mulch, it is important to consider where you will be using it and what you are trying to accomplish. Each type has advantages and disadvantages. Bark mulch will add nutrients to the soil as it breaks down, but you may need to replenish it periodically (a smaller bark mulch decomposes faster than a larger bark mulch. large). The pea gravel will transfer some heat to the underlying soil, which could help plants in cold weather. It could also cause the plants to grow too early in the spring, only to suffer from frost. For a full breakdown of mulch, see this CSU extension fact sheet: extension.colostate.edu/topic-areas/yard-garden/mulches-for-home-grounds-7-214.
After selecting the mulch, be sure to apply it to the recommended depth. To effectively suppress weed germination and prevent soil compaction, bark mulch and gravel should be applied to a depth of 3 to 4 inches; applying more than this can prevent air and water from reaching the soil. Cut grass or leaves can be added to a depth of 6 inches; allow layers of lawn mowing to dry before adding more.
When placing mulch around woody trees and shrubs, be sure to place it at least 6 inches from the base of the plant. Wet chips stacked against the trunk can keep the bark too wet, contributing to the growth of harmful fungi.
While it is common to apply mulch to black plastic or woven landscaping fabric to prevent weeds, CSU Extension does not recommend it. These barriers can restrict plant growth by preventing air and water from reaching the roots. Weed seeds can germinate above the barrier and root through the material, making the weed impossible to pull out. Organic mulches such as bark chips can improve soil as they decompose when there is no barrier between the mulch layer and the soil. The correct application of mulch eliminates the need for these barriers.
By mulching around plants, you help preserve their health while conserving water.
Submit your gardening questions to firstname.lastname@example.org or call 520-7684. In-person support is open 9 am to noon and 1 to 4 pm Mondays and Wednesdays at 17 N. Spruce St. Find on Facebook at Colorado Master Gardeners – El Paso County.