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Why Organic Mulch is so Important

by Paul Noe (a.k.a. Dr. Q)


As most of you know, there are basically two types of mulch: organic and inorganic. Organic mulch is made from products that were derived from living organisms, such as wood shavings, grass clippings, shredded bark, leaf mold, manure, or compost.  Inorganic mulch is made from materials that are mineral or manufactured, such as decorative rock, decomposed granite, rubberized, or plastic materials. Both types of mulch are appropriate ground covers that help to conserve soil moisture, inhibit weed growth and protect soil from erosion. However, organic mulch is the only type that actually works to condition and improve soil as it decomposes. It is one of the most important products we can use to protect and maintain healthy plants in our desert climate.

Conserves Soil Moisture:

Soil on white background

Good organic mulch can reduce the rate of moisture evaporation from soil by as much as 40 percent, and when it is mixed into the soil around plant roots along with a layer on the surface when planting, it can make the difference between plants making it through our hot summers or withering up and dying. As the mulch continues to decompose, it adds spongy humus to the soil which helps it retain moisture even longer. Plus, the humus breaks down to humic acid which helps to counteract the alkaline in our soil.

Improves Soil Texture and Conditioning:

Organic mulch harbors lots of beneficial organisms which work to keep the soil moist and fluffy, improving the overall texture, and reducing the potential for soil compaction.  This mulch is actually food for valuable soil creatures like earthworms and beneficial microbes that are essential to having a healthy soil, and thereby healthy plants. These organisms help the mulch to further decompose. As they do this, they are also processing nutrients for the plants, making the soil richer and more acidic.

Regulates Soil Temperature:

Salvia Flowers and Rock Retaining Wall at a Residential Home

Another huge benefit from organic mulch is that it helps to regulate soil temperature. It actually keeps the soil below it considerably cooler than bare soil in the same area. Soil covered by 2 to 3 inches of organic mulch is 8 to 15 degrees cooler, and in the winter, it insulates the soil to keep it warmer to protect surface roots from freezing.

A lack in organic matter in our desert soil, along with the lack of moisture it receives, makes it very difficult to grow things without the help of soil conditioners and amendments. Unless you want to grow only native desert plants in our soil, you have to add organic mulch when you plant, and continue to replenish it every year by adding it to the soil surface. The use of organic mulch is one of the best things you can do to turn our desert soil into productive soil for your plants.

Whether it is from your own compost pile, or in packaged products like our Dr. Q’s PAYDIRT Premium Planting Mix & Mulch, be sure to use a good organic mulch whenever you plant and as a surface mulch around all plants in your yard or garden!

PAUL NOE (a.k.a. Dr. Q)

Staff Horticulturist/Certified Horticulture Advisor

Star Nursery


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