University of Florida

The Neighborhood Gardener:
Soft and Squishy? Too Much Water is Trouble for Lawns

By Jack Tichenor, Extension Agent for UF/IFAS Extension Service, Manatee County

The month of August marks the peak of the rainy season in Florida. With more than seven inches of rain on average, this is great news for replenishing thirsty lakes and underground water reservoirs. But surprisingly, it could be bad news for your lawn, especially if your automatic sprinkler system is still operating routinely.

When you walk across your lawn is it soft, spongy, "squishy," and water-soaked? If so, your lawn is probably suffering from too much water. Excessive water promotes rapid growth of weeds such as sedge and dollar weed, fungus, and root rot. Shrubs can get leaf spot, die back, and suffer root decline. Lawns without good drainage become soft and muddy, especially in drainage swales between homes.

We can't do much about the rainy season, but we can manage our sprinkler systems so as to not add to the problem of too much water. Following are a few practical tips to help prevent overwatering your lawn.

During an active rainy season, just turn the irrigation controller off until several sunny, rain-free days pass. When you notice dry conditions in your lawn, temporarily switch the controller to automatic.

Install a rain sensor irrigation shut-off switch to prevent your automatic irrigation system from operating during and after a rainfall. One can be bought for around $25, anywhere irrigation supplies are sold, or an irrigation contractor can install one for you. It will pay for itself! Research has shown they will save 17 to 24 percent of your irrigation water. If you already have one, check to see that it is adjusted to the 1/2 inch setting and test it to verify it will stop irrigation if water is poured over it. See the EDIS publication "Residential Irrigation System Rainfall Shutoff Devices" for more information.

Adjust the irrigation controller for:

  1. What Day to Water: Be sure to follow water restrictions issued by your local municipality and local water management district. Often, homeowners are allowed to water twice per week. Use a rain gauge to know if a 1/2 inch or more rain has occurred a day or two before your allowed day; if so, turn the controller off and skip an irrigation to help prevent overwatering. True, the rain sensor shut off switch should take care of this but there is no substitute for being aware and involved.
  2. How Long to Water:  Most Florida soils need about 3/4 inch of water to moisten the root zone. But irrrigation controllers use minutes, not inches of water, for setting the zone run times. This dilemma is easily solved by using six to ten pet food or tuna cans to determine how long it takes to apply 3/4 inch of water. Just place the cans in a zone and note the minutes needed for an average of 3/4 inch water in cans. Repeat for all other zones. Zones using spray-type sprinklers usually need between 20 to 30 minutes; rotor-type sprinklers usually take 60 minutes or more.

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