Mulching for Healthy Plants, Water Conservation
by Keith C. Hansen, Extension Horticulturist
One of the number one methods of growing healthy plants and conserving water at the
same time is to use mulch in the landscape. Experienced gardeners have long known
the secret of mulching the garden and all its great benefits.
What is a mulch? It's simply a protective ground covering that saves water, reduces
evaporation, prevents erosion, controls weeds, and in the case of organic mulches,
enriches the soil. Almost sounds too good to be true!
Mulches can be classified as organic or inorganic. The organic mulches are most
popular and include straw, leaves, bark, pine needles, compost and similar materials.
Inorganic mulches include rocks, rock chips, synthetic fabrics, and other non-plant
materials.
A big advantage of mulching is it reduces soil moisture loss through evaporation.
Mulches also reduces the soil's exposure to wind which, in turn, reduces water loss
through evaporation.
The insulating quality of mulch helps to keep the soil cooler in the summer and warmer
in the winter. By maintaining more even soil moisture and temperature, mulch promotes
better root growth and plant health.
Erosion control also is important, especially in steep areas. Mulch helps to reduce rain
splash and runoff, which in some cases will also help prevent the spread of plant
disease.
Mulch also suppresses the growth of many weeds. A 3- to 4-inch layer of organic mulch
should be sufficient to prevent sunlight from reaching the soil, thereby reducing the
chance of weed growth. Any weed seedlings that do manage to germinate and break
through the layer of mulch are easily pulled. A mix of coarse and fine mulch will help
reduce seed germination.
Mulches should not be piled up against the trunks of plants, but rather form a donut
around the base of trees and shrubs.
Another benefit of organic mulches is that they enrich the soil as they decay, forming a
rich, dark organic material called humus that provides nutrients for the soil and
improves its texture.
Last but not least, mulch has aesthetic value. There is a range of colors and textures.
The uniform quality of most mulches when added to the garden floor serves much the
same aesthetic purpose as a carpet in a home.
So what are some of these marvelous mulches?
* BARK: This mulch is the most popular and widely available. Barks are available in
bags or can be purchased some places in bulk. Bark is relatively easy to apply, but
some types have a tendency to float away in heavy rains. Pine is the most common, but
cypress and redwood are popular. Cypress resists floating.
* CHIPPER DEBRIS: A mixture of shredded bark, wood chips and leaves from
tree-trimming operations, chipper debris is non-uniform so it's not as attractive as many
other types. A rustic effect for outlying areas of the yard where fine texture may not be
important. Also may create nitrogen deficiency as it breaks down unless first aged.
* PARTIALLY DECOMPOSED COMPOST: This makes an excellent mulch. You can
make your own compost or buy it. The lack of uniformity may make it less attractive in
exposed areas. Compost may also contain some weed seeds that can be
objectionable.
* LEAVES: Readily available and inexpensive, leaves work best if shredded before
applying as a mulch. Large, unshredded leaves tend to form an undesirable "mat"
which repels water.
* PINE NEEDLES: Great mulch, especially for acid-loving plants. Slow to decompose,
pine needles, last a long time. Avoid using near wood fences or walls due to potential
fire hazard.
* INORGANIC MULCHES: River stones, pebbles and gravel chips are all good
mulches. Though they do nothing to improve the soil, these materials can be striking,
and should be used carefully so they enhance rather than detract from the overall
landscape design. They will not require replenishing as frequently as organic materials,
but fallen leaves and other trash can detract from their uniform appearance and be
difficult to clean. White rock is very bright and reflective and may make surrounding
area hotter.
* LANDSCAPE FABRICS: Special woven fabrics that allow air and water to pass
through, while reducing weeds and evaporation. These materials can be used in
conjunction with other mulches. Fabric is laid on the soil and a mulch is placed on top.
Do not use solid sheet plastic which inhibits air and water movement and promotes root
rot.
Many fresh, undecomposed organic mulches, like sawdust, grass clippings, straw and
chipper waste, may draw nitrogen from the soil as the material breaks down, causing a
temporary nitrogen deficiency. Microbes tend to out-compete plant roots for the
available nutrients released as they break down. So, a recommendation is to allow
these materials to partially break down before using them, and/or supplement with
nitrogen fertilizer.
Since organic mulches decompose over time, they will need to be replenished or
replaced periodically. It's a good idea to check the garden every spring and renew
areas where the mulch has gotten thin. There is no need to remove the old and
replace with new mulch, since soil organisms will work the decomposing organic matter
into the soil, increasing the health of the soil.
Keith Hansen is Smith County Horticulturist with Texas Cooperative Extension. His web page is http://aggie-horticulture.tamu.edu/county/smith. Educational programs of Texas Cooperative Extension are open to all individuals without regard to race, color, sex, disability, religion, age or national origin.
Back to East
Texas Piney Woods Gardening Water Conservation Page
