The Homeowners Column

The Homeowners Column

Mulch to Conserve Moisture

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

There are a few things I don't know how I lived without–long underwear, flannel sheets, mulch and rain barrels. Obviously warmth and water are important to me. This year it looks like water will be a particular concern.

One way we can help our garden and landscape plants is to use mulch. Now is a good time to mulch since the soils are warm and moist. Mulches are any materials used on the surface of the soil. This broad definition could include organic materials such as wood chips, pine needles, straw, peat moss, corncobs and lawn clippings. Inorganic mulches would include river rock, ground tires, volcanic rock and synthetic fabrics.

Generally organic mulches are preferred for plant growth because of their ability to improve soil structure and provide a more natural environment for good root growth and, therefore, good top growth of the plant. Benefits of organic mulches include:

  • Conserving soil moisture. Mulches can also increase water penetration into the soil.

  • Maintaining a uniform soil temperature by insulating the soil. Mulches keep the soil warmer during cool weather and cooler during warm weather.

  • Minimizing soil erosion and compaction from heavy rains, heavy lawn mowers, heavy people and heavy thoughts.

  • Improving soil structure through the decomposition of organic mulches. This is particularly important in heavy soil types. Mulches keep clay soil from cracking after rains. Mulches encourage worm activity and other beneficial life in the soil.

  • Reducing weed problems by preventing weed seed germination.

  • Keeping lawn mowers and string trimmers away from tree trunks and surface roots. Few things will bring a horticulturist to tears faster than to see tree trunk damage due to lawn mower blight. Once a tree is damaged from lawn mowers scrapping the trunk or string trimmers bruising the trunk, little can be done to correct the damage.

Some disadvantages of organic mulches include:

  • Fresh materials could cause nitrogen deficiency as they decompose, if fertilizer is not added regularly. Fresh mulch should be composted for at least three months before use.

  • Fine textured mulches such as sawdust or grass clippings may retain too much moisture so should be applied in several thin layers or they should be used mixed with a coarser material.

  • Generally mulches such as pine needles and oak leaves are not going to cause dramatic changes in the acidity or alkalinity of the soil as is often believed.

Mulching recommendations:

  • Apply composted material to the soil surface and top with coarser and fresher material. Incorporation into the soil is not recommended or necessary.

  • Mulch should be about 4 inches deep. Do not exceed 6 inches in depth.

  • For trees the larger the mulched area the better, but it should reach at least to the tree's drip line (the outer perimeter of the branches).

  • Keep mulch at least 6 inches away from the tree trunk and a couple inches away from plant stems.

Check out the Landscape Recycling Center at 1210 East University Avenue in Urbana. Mulch is available in different particle sizes. The finer premium woodland mulch is great for flowerbeds. The coarser chips are good for paths. They also have garden compost and mushroom compost. Hours are 8-4 Monday through Saturday. They even deliver for a small fee. Call 344-5323.

Grand Prairie Friends is having their plant sale May 13 in front of Knollwood Shoppes 2215 South Neil in Champaign from 9-3. They always have wonderful selection of prairie and woodland plants. Many prairie plants are known for their durability, beauty in flower gardens and ability to withstand dry conditions.

C-U Herb Society Plant Sale May 6 from 9-2 at Urbana Free Library.

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