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Extension > Garden > Yard and Garden > Soils > Composting and mulching guide > Use of compost as a mulch

Use of compost as a mulch

Mulches are used in gardens to suppress weeds, conserve soil moisture, reduce soil erosion, and modify the soil temperature (makes it cooler in the summer, reduces rapid decline and fluctuation in the winter). Yard waste compost makes an ideal mulch for annual and perennial gardens. All you need to do is apply a 2-4 inch layer of compost around the base of the plant. Periodically throughout the summer, you may need to add more compost over the old layers to maintain the benefits of the mulch. The soil environment beneath the mulch is favorable for earthworms, which are valuable for aerating the soil. Organic matter is gradually added to the soil as the mulch decomposes.

For annual gardens, the mulch can be worked into the soil at the end of the season to further improve the soil. For perennials, it may be beneficial to remove the mulch in the spring to allow the soil to thaw out faster. As discussed above, well-decomposed yard waste compost will not tie up nitrogen. Therefore, it is not necessary to add nitrogen beyond that recommended for plant growth. If noncomposted or partially composted leaves are used, one tablespoon of a high nitrogen fertilizer (for example, 27-3-3) should be applied to each five-gallon bucket of mulch.

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