Primetime Newspapers
By Calvin R. Finch, PhD,
SAWS Water Resources Director, and Horticulturist
Week of May 29, 2006 
“SIP for Your Lawn”  

            Are you like most San Antonio area residents and want to have a healthy lawn, but do not want to waste any water?  The SIP could be perfect for you.  SIP stands for Seasonal Irrigation Program.  It is a program that uses weather data (also called Potential Evapotranspiration (PET) to determine how much irrigation that a lawn requires in any week.  Farmers have used the same information for their crops for years in arid regions.  Over four years, 1996 – 2000, SAWS and the Texas Cooperative Extension adapted the PET concepts to area lawns by studying the response of 64 lawns to different regimes of watering.

 

            The tests determined that PET worked to determine how much water that a lawn needed.  They also determined that for a lawn in full sun the water could be applied once per week and that St. Augustine grass and zoysia required the most water to stay green, Bermuda grass about 33% less, and buffalo grass about 50% less.  In the shade, St. Augustine grass and zoysia grass required about 33% less water than they did in full sun.  Bermuda grass and buffalo grass will not survive in the shade.

             These test results translate to about ¾ inch per week, on average for zoysia and St. Augustine in the sun.  Bermuda grass requires about ½ inch per week in the sun and buffalo grass about 3/8 inch water.  In the shade, zoysia and St. Augustine grass requires ½ inch of irrigation on average.  You could water your lawn successfully using these averages, but the best way to use the test data is to sign up for SIP.

 

            Visit the SAWS website at www.saws.org, click on “Conservation” and then again on “SIP.”  At this site you can sign up to receive a free weekly watering recommendation by phone message or e-mail message.  The recommendation is personalized for your lawn because the sign-up requires that you relate your lawn grass variety and the amount of sun the lawn receives.  Homeowners who would like to use the SIP recommendation, but prefer not to receive an e-mail or phone message can listen to Gardening South Texas from noon – 2:00 p.m., either Saturday or Sunday.  The program is on KLUP radio at 930 on the am dial.

 

            Individuals who sign up to use SIP on the SAWS website will be mailed a SIP kit.  The kit includes instructions and specialized rain gauges so you can determine how much water your irrigation system is applying. A SIP kit is also provided to attendees of SAWS gardening events and/or events sponsored by the Bexar County Master Gardeners and the Gardening Volunteers of South Texas who agree to follow SIP recommendations.  Homeowners that follow SIP recommendations save 20% of their water use on average and have green healthy lawns.

 

            Other things you can do to have a water efficient lawn is to have at least four inches of soil under the grass; aerate and top dress every 1 – 2 years; and water effectively.

             The new San Antonio Water Conservation Ordinance requires that new home builders provide at least four inches of soil under any lawn grass.  Improve water efficiency even more by requiring that at least 25% of the soil is compost (1 – 2 inches incorporated into the soil).  For your established lawn, aerating and top dressing with compost in late winter will maintain or improve soil quality.

 

            Water effectively by repairing leaks in your irrigation system.  A zoned system is more efficient than a system that waters shrubs and groundcovers at the same time as it waters lawn grass.  Shrubs, trees, and groundcovers do not need to be irrigated as often as lawn grass.  The new Water Conservation Ordinance requires that new homes with a lawn must have the landscape irrigated with a zoned system.  If you have any questions please call SAWS, Conservation Department at (210) 233-3659.