WHAT, WHY, HOW TO USE MULCHES

Cochise County Cooperative Extension Home Horticulture
Environmentally Responsible Gardening & Landscaping in the High Desert 

What is Mulch?

Mulches are organic or inorganic materials that cover the soil around the root zones of plants.
bullet Organic mulches (bark or wood chips, leaf mold, grass clippings, compost, hay, straw, newspaper) will break down over time and will need to be replenished. Keep them a couple of inches away from trunks and stems as moisture can cause rotting. They can also blow or float away with our strong winds and heavy rains. Organic mulches add small amounts of nutrients and cool the soil.
bulletInorganic mulches (gravel, decorative rocks, sand, boulders, decomposed granite) have a long lifetime and may need to be top-dressed or raked every once in awhile. Inorganic mulches add no nutrients and warm up the soil.

Why use Mulch?

bulletMulching prevents moisture loss, therefore extending periods of watering by days, sometimes even by weeks!
bulletBy shading the soil, mulches inhibit weed growth. What weeds do get through are easy to pull, and weeding will decrease as time goes by.
bulletKeeps soil from splashing onto plant leaves, thereby reducing certain diseases.
bulletMatching the right mulch to the type of plant or crop can enhance plant growth.
bulletGravel or rock mulches can prevent rainwater runoff.
bulletBest of all, mulches reduce work and adds a finishing touch to the landscape.

How do I use Mulch?

bulletA good rule of thumb is to apply mulch at least 2-3 inches deep around the root zone of trees, shrubs, flowers, vegetable gardens, and even to outdoor and indoor container plants.
bulletWeed fabric may be used under the mulch as an added measure to keep weeds down – NOT black plastic as it does not allow the exchange of water and oxygen that plant roots require. Plastics also permit rainwater to runoff the property – you want to retain it!
bulletIf plastic is already installed you can take a garden fork and punch holes in it, especially around the perimeter of plants, especially trees, to allow water to penetrate the feeder roots which will improve the health of plants.
bulletFor paths, newspaper, old carpeting, cardboard, or other such materials, covered with mulch, will provide excellent weed suppression.

Be creative with mulches. Use different textures and colors to define areas. Also use the appropriate mulch for different situations. Most native plants enjoy rock mulches, thriving on the reflected heat. Roses and other "exotic plants’ on the other hand prefer bark mulches. And don't forget the vegetable garden, it will greatly benefit from organic mulches (particularly alfalfa hay) and at the end of the season dig it under to improve soil structure. Experiment and see what works best in your garden. Take note in neighborhood yards, city plantings, and in botanical gardens not only the plants but the mulch used and duplicate it in your setting.

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