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Mulch

Mulch It! Mulch conserves water, prevents weeds and feeds the soil.

What Is Mulch?

Mulch is any material, such as wood chips, grass clippings, leaves or compost, that is spread over the surface of soil.

• Grass clippings: Spread in thin layers over vegetable and flower beds, or mix with leaves and spread in a thicker layer.
• Deciduous tree leaves: Spread as mulch in the fall.
• Evergreen leaves: Use these on pathways because they take longer to decompose.
• Chipped or shredded woody waste: Spread three to six inches deep to make a good-looking, long-lasting mulch or path cover.

What Does Mulch Do?

• Retains water.
• Inhibits weed growth.
• Keeps soil temperatures from becoming too hot or too cold.
• Protects sloping ground from soil erosion.

How Do I Apply Mulch?

• Weed the area first, then spread mulch around plants to the drip line or cover the entire garden bed.
• Mulch can be spread thickly if water can penetrate it to reach the soil and if it does not smother the roots of the plants being mulched.
• Three inches of mulch can be safely used for any woody plant, and up to eight inches can be used for large trees.
• Thick mulches are harmful to shallow-rooted plants such as rhododendrons and azaleas. Mulch should be kept a few inches away from the trunks of trees and shrubs to prevent damage to the plants from disease and rodents.

Where Can I Find Mulch Materials?

Every yard has grass, leaves or other green or woody materials that can be made into mulch. If chipped or shredded woody wastes are needed, contact tree services listed in the Yellow Pages. Some wood shops and coffee roasters make their organic byproducts available to customers and the general public. Call ahead to check on supplies. Visit King County's GroCo compost information page to learn how biosolids compost can be used as a mulch around plantings.

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