Water Conservation and Technology Center

Essential Ingredients for Good Lawns and Gardens

November 16, 2012

By Calvin R. Finch, Ph.D., Horticulturist and Urban Water Program Director, Texas A&M Institute of Renewable Natural Resources

Compost and mulch are essential materials for successful lawn care and gardening in San Antonio. Take the opportunity this fall to use them generously in your landscape.  

Compost is decomposed organic material that is a wonderful soil amendment. The material makes the soil better at holding water and at the same time improving drainage. This may sound contradictory but it occurs because the particles that form in the soil hold water for easy use by the plant but the particles also form channels between them that allow excess water to flow out of the root area.

Compost also contributes to more efficient use of nutrients and a texture that makes root growth easier. The net result is a better garden and lawn.

Apply 2 inches of compost to your garden and incorporate it into the top 6 inches of soil with a tiller or by shoveling. The best way to enrich the lawn with compost is to aerate and then spread one half inch of compost over the surface. The compost filters into the aeration holes to reach the root zone.

The most effective aerator is the one that cuts a plug of soil and deposits it on the lawn surface. If your favorite rental store does not have an aerator, call around.

Mulch is usually organic material, but it is often not decomposed. It contributes to water conservation when it is applied to the soil surface over plant root systems. The mulch insulates the soil, reducing evaporation and soil temperatures. Mulch allows roots to spread throughout a larger soil reservoir, which is especially important in our thin and/or poor quality soils. Mulch also reduces competition from weeds.

Four inches of mulch over the root system of a newly planted tree or shrub contributes to faster growth. There are many good types of mulch including shredded brush, shredded cedar, pecan shells, leaves and pine bark. Compost also makes good mulch but is more valuable as a soil amendment.

Use the finer mulch materials such live oak leaves for the soil between rows in the flower or vegetable garden. One inch of leaves makes a good walking path and reduces water loss in addition to reducing weed germination.

Mulch and compost can be purchased from several horticultural suppliers in the San Antonio area. Among the suppliers are Quality Organic, Keller Material, Fertile Garden Supply, Garden Ville and both mulch and compost cost about $30/cubic yard. Delivery charges add about $75 per load. A load can be 12 yards or more.

A cubic yard of compost spread at one half inch on your lawn will cover about 648 square feet of lawn. If you use it 2 inches deep in your garden, it will cover 162 square feet of garden.

You calculate your mulch needs the same way. Once cubic yard of mulch spread 4 inches deep will cover 81 square feet of surface.

It will cost about $435 for the 12 cubic yards of compost required for a 8,000 square foot lawn. Six cubic yards of mulch can cover an 8 by 60 feet shrub border 4 inches deep for a cost of about $215.

The cost of these materials and the work required to spread them are worth it for better gardens and lawns plus water savings.

There is a special incentive now if you are a SAWS customer to buy compost and/or mulch. The water purveyor is encouraging the use of these water-saving materials this fall by offering a generous credit on your water bill. Complete the required application and provide original receipts for the rebate.

If you purchase 2 to 5 cubic yards of mulch or compost, you receive $75. Purchase over 6 cubic yards and you receive $150. A family can receive one mulch rebate and one compost rebate. Rebates for commercial customers are also available.

The rebates are available until Dec. 31, 2012 or when the allocated funds are used up, whichever occurs first. Obtain the one page easy-to-complete application and all the other information required to take advantage of the incentives at saws.org/conservation/rebates/.

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