Established lawns and landscapes need not be watered daily. Deep, infrequent irrigation is better than frequent sprinklings. Two irrigation periods per week are usually sufficient except during extremely hot, windy periods.
The amount of water that is applied is just as important as the frequency.
The time of sprinkling means nothing, unless there is a correlation between that and the volume of water that is applied. The amount of water that is delivered by an irrigation system is determined by pipe size, pressure and the number of specific sprinkler heads that are used.
Since no two irrigation systems are the same, each one should be calibrated in order to determine the exact amount of water that is being applied. Established lawns should be given one-half to three-quarters of an inch at each irrigation. Most established landscape plants will do just fine with this amount of water, too.
Find out how much water your system is delivering and make any necessary adjustments. Placing five or six straight-sided cans or pans at random throughout the area to be irrigated can easily do this. Run the system a predetermined amount of time and, using a ruler, check the depth within the pans.
Continue to check the pans and keep up with the sprinkling time until an average of one-half inch is collected in the pans.
Most gardeners who perform this relatively simple test are shocked by the results. In many cases it is determined that only a fraction of what is needed is being delivered. On the other hand, the system is sometimes found to be delivering excessive amounts of water, which is wasted.
Some homeowners say that no matter how much they water, certain spots in their lawn seem to wilt soon after irrigation. Wilted spots in lawns (those light gray, sickly looking areas) will show up more frequently during period of dryer, warmer weather. Be sure to check to see if your sprinkler pattern is overlapping properly and providing uniform coverage. This can be done using the pans, as described previously.
A second cause for those dry areas could be differing soil textures within the lawn. Sometimes differing textures of soil are used for filling different areas during construction. In other words, the spots that dry out more quickly could be because the soil is more sandy or porous in those areas. If this is the case, consider watering these areas with spot watering sprinklers between regular irrigation times, instead of watering the entire lawn.
For additional, reliable information on lawn watering, contact your UF/IFAS County Extension Office or visit http://edis.ifas.ufl.edu/topic_lawn_watering.