Primetime Newspapers

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist

Week of May 19, 2008

 

“Watering Advice”

 

            Last week with a few days over 90°F, lots of wind, and plants growing actively, the soil in our gardens and lawns dried out.  In this kind of weather, many plants in a landscape situation do need the water we provide through hand-watering and irrigation.  To provide that water efficiently and to keep the water bills reasonable, consider these suggestions.

 

·      If you have a sprinkler system, have your irrigation company service the system now and every six months.  They should adjust heads and fix any leaks.

 

·      If you are a SAWS customer, call (210) 704-7283 for a free sprinkler system audit.  The auditor will determine if you have any leaks, look for poorly performing sprinkler heads, and check the settings on your controller.

 

·      Most lawns require irrigation once/week to stay green.  If you have less than four inches of soil, you may have to run the sprinklers two times per week.  If your sprinkler is operated more than once/week, use less water for each application because the soil reservoir is smaller and it cannot store as much water. 

 

·      Every sprinkler system is different and even the heads in a sprinkler system can be different.  For a relatively accurate measurement, place several pie plates on the yard and see how much water is applied in 15 minutes.  If the plates average one-half inch in the 15 minutes you will know that your sprinkler heads on the average, apply one inch of water in 30 minutes. 

 

·      It works best in terms of efficiency if you change the amount of water you apply each week to your lawn based on the weather.  One option is to sign up for a personalized SIP recommendation to be e-mailed to you once per week on the day you designate.  SIP uses the week’s weather to determine exactly how much water to apply.  To enroll in SIP, visit the SAWS’ website at www.saws.org, click to Conservation and then to Seasonal Irrigation Program (SIP).  Many modern controllers can be set to apply .5, .75 or 1 inch of water (based on time), and then you just select which of the options to use that week based on the SIP advice.   

 

·      If you would rather just irrigate the same amount each week because your controller does not have the option to have more that one setting programmed at a time, consider this recommendation.  Every week for St. Augustine or zoysia in the sun, apply .75 inch of irrigation.  For St. Augustine or zoysia in the shade, apply .50 inch of water.  Also apply .50 inch of irrigation for Bermuda grass in the sun.  Buffalo grass takes about .75 inch of irrigation every two weeks.  Even with buffalo grass it works best if it is irrigated every week.  Set the sprinkler for the amount of time it takes to apply 3/8 of an inch per week. 

 

·      Container plants will need to be watered at least once/week and probably twice per week, especially if the top is large in comparison to the container.  A larger container is a larger reservoir.  Apply enough water that the whole container is moistened and water begins to seep out the drainage hole.  

 

·      Most established trees and shrubs have much more drought capacity than the lawn grasses do.  A lawn may go dormant if it does not receive rain or irrigation at least every two weeks.  Trees and shrubs can retain their leaves in the midst of summer long droughts.  If you decide to water your trees or shrubs once/month in a droughty summer, water with a leaky hose or let the hose run on the drip line for a long enough time that water soaks in to six or eight inches.  A once/month soaking is especially desirable for blooming plants such as modern tough or old-fashioned roses.

 

·      Water newly plant trees and shrubs every time the soil under the mulch dries the first summer.  Water generously at the base of the plant.  Drought-tolerant plants are slow to put their roots into a droughty soil.

 

·      Water most annual flowers and vegetables at the same frequency as you do containers.  Twice per week is often necessary to produce food or flowers.  Mulch the plants and use drip irrigation or a leaky hose for most efficiency.