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Never mind color — here’s why mulch is good for plants

Woodchips are easily obtained in bulk for mulches that weather to a natural organic color the first season in the garden.
Woodchips are easily obtained in bulk for mulches that weather to a natural organic color the first season in the garden. TNS

Brick red-dyed mulch is the equivalent of the 1970s orange shag carpet. It was popular for about two minutes and then became the ultimate downer after the fad passed. Unfortunately, colored wood chips are still around, which makes no sense when natural-looking alternatives are available.

Mulch is a term applied to anything you spread out on top of the ground, from straw to wood chips. While these mulches are organic matter, they are not compost and are not suitable for tilling into the soil and can actually reduce overall fertility if you do. In fact, the best mulches are made from woody organic matter that resists decomposition so it remains effective for a very long time.

When soil is covered with mulch three good things happen. First, the earth is perpetually shaded from the hot summer sun, keeping its surface temperatures low so plant roots don’t heat up.

Second, mulches seal in the water. When there isn’t any drying between water applications (or summer rain), plants don’t suffer the wet-dry yo-yo effect that occurs with fully exposed soils.

Third, mulch blocks sunlight from direct exposure to soil around plants where weed seeds often sprout. With mulch in place, weed seeds still germinate, but the seedling dies quickly if the new shoot doesn’t reach sunlight.

Mulch needs to be at least 2 inches deep to provide these benefits. Mulch layers can be thicker, particularly when using fluffed up material like baled straw because it gradually mats down from watering or being walked on. Never pile mulch up around the base of any plant be it a tree or a tomato, or you risk rotting the stem and killing the plant.

Mulches can be decorative or practical. That red dyed wood chip mulch is supposed to be a decorative choice for beds and borders, but it’s not a natural color. Chips allowed to weather to a more appropriate hue or earthy ground bark is a much better choice.

When you select a practical mulch, it should be both cheap and plentiful. You can use bales of alfalfa or grass hay that are more expensive, but if you inquire about spoiled bales, which can no longer be used for livestock, they are much cheaper or sometimes free from feed stores. These compacted bales are easy to transport, fluff up to an incredible amount and don’t contain any toxins or chemicals. Unlike other mulches, alfalfa hay contains nitrogen, which adds some benefit to the soil.

Maureen Gilmer is an author, horticulturist and landscape designer. Learn more at www.MoPlants.com.

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