By B.J. Jarvis, Pasco Cooperative Extension Horticulture Agent and Director and
Jack Tichenor, Manatee Extension Service Horticulture Agent
August marks the peak of Florida’s rainy season with 3/4 of the year’s rainfall occurring during the summer months. This can be a blessing and a curse.
The good news is rainfall replenishes thirsty lakes and underground water reservoirs, but it can be too much of a good thing for our landscapes. Gardeners can make this even worse if the automatic irrigation system is still operating routinely.
Is the lawn soft, spongy and “squishy” when you walk across it? If so, your lawn is probably suffering from too much water. Excessive water promotes thatch, weeds, fungus and root decline. While gardeners can’t control the rain, we can effectively manage our irrigation systems to minimize over-watering. Following are a few practical tips to help prevent mismanaging water in the landscape.
Rain gauges cost less than $5 and pay for themselves in no time. How often have you been unsure how much rain fell at your place after a downpour? A cheap rain gauge can help you see if your garden got the downpour or if it is thirsty.
In-ground irrigation systems must have a functioning rain sensor shut-off, as it is mandatory on any system installed after 1993. These gadgets are designed to prevent automatic irrigation systems from operating during and after a rainfall. Such sensors are cheap at around $25 and will pay for itself quickly. Research has shown they will save 17 to 24 percent of irrigation water with a functioning rain sensor.
Also, check existing sensors to assure they are adjusted to the 1/2-inch setting. Then test it to verify the irrigation system will not run when water is poured over it.
Irrigation controllers need to be set for the right day and the correct duration. Currently Pasco County irrigation restrictions limit watering lawns to a once-per-week schedule, but keep in mind that just because “it’s my day” doesn’t mean the lawn and landscape plants need to be watered. Set systems to off during the summer rainy season since frequently watered landscapes can go a week or two without running the system if Mother Nature spaces rainfall nicely.
As for the length of watering, most Florida soils need about 3/4-inch of water to moisten a one-foot root zone. However, irrigation controllers use minutes, not inches for setting the zone run times. This dilemma is easily solved with 6-10 tuna or other straight-sided cans to determine how long it takes to apply this amount. Just place the cans randomly in a zone and run the system on the normal cycle. If cans hold more than 3/4 inches, then cut down the run time. Repeat for all zones.
Too little water can be just as bad as too much; make sure enough is flowing. Watering the top few inches of soil will encourage shallow, sensitive roots. In general, zones using spray type sprinklers usually need between 20-30 minutes while rotor type sprinklers can take 60 minutes or more to deliver this amount application.
Water management is critical even in sub-tropical west-central Florida. Applying just the right amount along with the right timing means the difference between a well-adapted landscape and one that is prone to fungus, thatch and loaded with weeds. These few simple monitoring efforts will pay big dividends this summer.
Additional information about irrigating turf can be found at the University of Florida’s electronic database at edis.ifas.ufl.edu/pdffiles/AE/AE14400.pdf.
-B.J. Jarvis and Jack Tichenor are University of Florida horticulture experts from Pasco and Manatee counties respectively. Jarvis can be reached at .