Instead, the pieces must be picked out of the soil and disposed, which negates much of their value as a low-maintenance material. But unlike organic mulch, they add no nutrients to the soil. Although gardeners frequently use synthetic mulches underneath more aesthetic materials in landscapes intended to be low-maintenance, these materials will eventually break down. They can increase runoff from rainfall and, ironically, also trap moisture in waterlogged soils. These materials may help warm the soil but they will not insulate against temperature fluctuations. Synthetic materials such as landscape fabric (also known as geotextile) and black plastic are commonly used, but they do not perform well for most of the tasks mulch is meant to accomplish. While gardeners may choose to use them in certain circumstances and locations, these materials are generally not the best choice for most ornamental landscapes. Like “beauty bark,” many materials sold as mulch do not perform well for that purpose. Although decorative bark dust is a popular mulch, wood chips such as those pictured above are much more beneficial to your soil. Note that wood chips are not the same as bark mulch, which has different properties and is not as beneficial. They have also been found to encourage mycorrhizal fungi and disease-suppressing microbes. In a study of 15 materials, wood chips were best at retaining moisture, moderating soil temperature, and suppressing weeds. Wood chips are arguably the perfect landscape mulch. Fortunately, its friable texture makes weeds growing in compost mulch easy to pull. Sometimes called a feeding mulch for its high nutrient content, compost is often the mulch of choice in annual beds and newly planted areas where coarse wood chips could damage tender new stems.Ĭompost encourages soil fauna to thrive. Be sure to select groundcover that is native to your region. These are useful for overwintering vegetable gardens, where they prevent erosion and improve soil tilth. Sometimes ground cover plants, especially nitrogen-fixing species like clover, are called living mulches. But each material will function a little differently and impart a different look to your landscape. Nearly any organic material can be used, including compost, bark, wood chips, leaves, seed hulls, grass clippings, nut shells, newspaper, cardboard, or straw. Organic in this case means “derived from living organisms.” Organic mulches are biodegradable, plant-based materials that add nutrients to the soil as they break down. The best mulches are organic materials, not in the USDA-certified sense of “free from synthetic chemicals,” although that is also a good idea. That’s why we’ve put together this Mulching 101 primer.

Different materials will accomplish some of these tasks better than others. Over time, mulch can also improve soil tilth and fertility. You can use mulch to modulate soil temperature, retain soil moisture, and suppress weeds. Instead, layer mulch over the top of the soil. Unlike soil amendments, you should not mix mulches into the soil. But mulching correctly - that is, in a sustainable manner that benefits the plants growing in your garden - can be confusing. Mulch is any material you use to cover bare soil in a landscape.

Living earth mulch