The Lawn Whisperer

Pay Attention, and Your Grass Will Tell You When it Needs Watering and Fertilizer

Q: What’s the best way to water my lawn? I want to be responsible in my use of water but I also want to make sure I water adequately.

Good for you. We all need to think more about how much we water, where we water and how we apply the water to our lawns and our planting beds. Fortunately, we had a decent amount of rainfall in summer of 2012 so watering wasn’t really needed. Fall was a bit dry, though, and we really don’t know what to expect this summer. Having a watering plan will help make sure your lawn gets what it needs without wasteful over-watering.

When we talk about watering, we also need to talk about fertilizing and mowing. Many people apply far too much fertilizer and water to their grass, because they want that lush, green “golf course” look to their yard. But overwatering can damage your grass and cause problems on property other than your own. The excess fertilizer washes away, causing pollution in our lakes, springs and streams and damaging the ecological balance downstream. Most people fertilize their lawns too early in the year, too. When the soil and roots are still cool, the plant can’t absorb all the nutrients so you’re wasting your money and your effort. Centipede grass, in particular, will turn yellow if you fertilize too early.

It’s tempting during those warm March days to get out the bag of “weed and feed,” but find another outdoor chore to do instead. The soil doesn’t warm as quickly as the air. Wait until early April, when your lawn has started to “green up” on its own, to apply fertilizer.

An established lawn in North Florida and the Panhandle needs one-half to three-quarters of an inch of water per week, depending on the type of soil you have. Clay and loam soils retain moisture more than sandy soils, so half an inch is probably enough; use the higher measure for sandy soil. Get a rain gauge, so you’ll know how much water Mother Nature is providing. If you’re getting at least half an inch of rain a week, you don’t need to water. Overwatering will cause shallow root systems to develop, which makes the grass less drought-tolerant than it would be with a deeper root structure. It also encourages the development of thatch, a matted layer of dead plant tissue at the base of grass blades that prevents water, sunlight and nutrients from reaching the roots. Overwatering also makes your lawn more susceptible to disease, pests and weeds.

In tandem with proper fertilizing and watering is proper mowing. St. Augustine cultivars should be 4 inches high; centipede should be 3 inches. Contrary to popular myth, the clippings don’t contribute to thatch buildup, so leave them where they fall to feed the lawn.

Cutting grass too short limits its drought-tolerance, and cutting too much at one time stresses the plant. Never cut more than a third of the height at one time.

Lawn-watering systems use overhead sprinklers. Many come with automatic timers, but if you want to be responsible about your water usage, set it to manual control. We’ve all seen it: It’s pouring rain and someone’s lawn sprinkler is on. Don’t be that guy. Go look at your grass and see if it’s asking for water. If it is, turn on your sprinkler system.

You can check your system to see how much water it is dispensing, how fast and where it’s landing by placing empty cans — short ones such as tuna cans or cat-food cans work great — around your yard. Mark the inside of the cans with a waterproof marker at quarter-inch intervals, set them out and then see how much was collected in 10-minute intervals. Then you can figure out how long to leave the sprinklers on to get the right amount of water where it needs to be. You’ll also be able to see whether you have any dry spots in your lawn that the sprinkler isn’t covering.

Water your lawn early in the morning to reduce water loss from evaporation as well as reduce the chance of lawn disease.

Your lawn will tell you when it’s time to water it. The leaf blades will fold and curl in an attempt to retain moisture. The color will also change from green to a blue-gray. Perhaps the most visible sign a lawn needs watering is footprints that remain long after they were made. If you don’t see at least one of these signs, don’t water.

© 2013 PostScript Publishing, all rights reserved. Audrey Post is a certified Advanced Master Gardener volunteer with the University of Florida/IFAS Extension in Leon County. E-mail her at or visit her website at Ms. Grow-It-All® is a registered trademark of PostScript Publishing.

Categories: Gardening