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Mulch is any materials you employ to cover bare soil in a panorama. But mulching appropriately — that’s, in a sustainable method that advantages the crops rising in your backyard — might be complicated.
Unlike soil amendments, you shouldn’t combine mulches into the soil. Instead, layer mulch excessive of the soil. You can use mulch to modulate soil temperature, retain soil moisture, and suppress weeds. Over time, mulch may enhance soil tilth and fertility. Different supplies will accomplish a few of these duties higher than others. That’s why we’ve put collectively this Mulching 101 primer.
Good Mulching Materials
The finest mulches are natural supplies, not within the USDA-certified sense of “free from artificial chemical compounds,” though that can be a good suggestion.
Organic on this case means “derived from residing organisms.” Organic mulches are biodegradable, plant-based supplies that add vitamins to the soil as they break down. Nearly any natural materials can be utilized, together with compost, bark, wooden chips, leaves, seed hulls, grass clippings, nut shells, newspaper, cardboard, or straw. But each material will operate slightly in a different way and impart a distinct look to your panorama.
Sometimes floor cowl crops, particularly nitrogen-fixing species like clover, are known as residing mulches. These are helpful for overwintering vegetable gardens, the place they stop erosion and enhance soil tilth. Be certain to pick out groundcover that’s native to your area.
Just a few good floor cowl choices are:
Sometimes known as a feeding mulch for its excessive nutrient content material, compost is usually the mulch of selection in annual beds and newly planted areas the place coarse wooden chips might injury tender new stems.
Compost encourages soil fauna to thrive. However, compost additionally encourages weeds. Fortunately, its friable texture makes weeds rising in compost mulch straightforward to drag.
Wood chips are arguably the proper panorama mulch.
In a study of 15 materials, wooden chips had been finest at retaining moisture, moderating soil temperature, and suppressing weeds. They have additionally been found to encourage mycorrhizal fungi and disease-suppressing microbes. Note that wooden chips should not the identical as bark mulch, which has completely different properties and isn’t as useful.
Poor Mulch Materials
Like “magnificence bark,” many supplies offered as mulch don’t carry out nicely for that function. While gardeners might select to make use of them in sure circumstances and areas, these supplies are typically not the only option for many decorative landscapes.
Synthetic supplies resembling panorama material (often known as geotextile) and black plastic are generally used, however they don’t carry out nicely for a lot of the duties mulch is supposed to perform. These supplies might assist heat the soil however they won’t insulate in opposition to temperature fluctuations. They can enhance runoff from rainfall and, paradoxically, additionally lure moisture in waterlogged soils.
Permanent weed management is a myth. Although gardeners often use artificial mulches beneath extra aesthetic supplies in landscapes supposed to be low-maintenance, these supplies will finally break down. But not like natural mulch, they add no vitamins to the soil. Instead, the items should be picked out of the soil and disposed, which negates a lot of their worth as a low-maintenance materials. Plastics and material are helpful for soil solarization and for seasonal use in vegetable gardens the place they’re simply pulled up on the finish of a rising season.
Gravel and Rock
Inorganic mulches like gravel and rock are nonbiodegradable pure supplies, however they nonetheless have to be replenished each few years.
They are mostly utilized in Zen gardens and desert xeriscapes as an alternative to grass. But they don’t seem to be notably efficient in planted gardens.
How to Mulch
You can use a thick layer of mulch to smother a weedy space. But in a planted mattress, you need to unfold mulch 3-4 inches thick over well-watered soil.
You don’t must take away outdated mulch from a planting mattress — merely layer new materials to keep up the specified complete thickness on prime of outdated mulch. If your outdated mulch continues to be 3-4 inches thick, there isn’t a want so as to add extra.
Keep mulch away from plant stems. Piled in opposition to the trunk of a tree or shrub, mulch may cause the stem to rot.
When to Mulch
Mulch a few times a yr, in spring and fall. In spring, mulch as soon as the soil has thawed, however ideally earlier than weeds have an opportunity to turn out to be established. Do not mulch over soil that’s both completely dry or waterlogged.
Apply mulch to new plantings in fall. In areas the place the bottom stays frozen all winter, enable crops to go dormant earlier than mulching after the primary frost. In areas the place frost is uncommon or intermittent, mulch early to keep away from freezing soils solely.
This article was initially revealed on September 18, 2019.