July 16, 2019

When and How Much to Water the Lawn

Unless you irrigate from a well or other private source, watering the lawn can be an expensive enterprise, especially during hot, dry summers. Watering efficiently will save you money in the long run, and will also help during dry spells when communities often restrict water usage. The goal of any successful watering plan is to use as little irrigation as possible while keeping your grass green and healthy.

Lawns generally require a half inch of water from rain and/or irrigation twice per week. Of course, many factors affect your particular lawn’s needs during any given week. The following guidelines will help you decide what’s right for your lawn.

How often to water?

Conditions of your yard, including the type and variety of grass, the quality of soil, and the amount of shade, all directly affect how often you need to water your lawn.

For example, zoysia tends to need watering more often than most varieties of Bermuda, and grass grown in sandy soil needs more frequent watering than the same variety grown in clay soil. Shady areas, however, hold onto moisture longer and may need less frequent watering than areas in full sun.

If these factors were the only ones affecting water needs, scheduling would be fairly straightforward, but ever-changing environmental conditions like wind, heat and hours of sunshine can increase your lawn’s need for water, and extended dry spells can also make lawns thirstier.

What to watch for when watering

Start by following the twice per week guideline as a good rule of thumb for watering frequency, but also keep a constant eye on your lawn. It will tell you if and when it needs more frequent watering. Thirsty grass will look stressed.

The color will turn a dull blue-green, and the blades will often curl or fold. If you walk across the grass and your footprints remain visible, that’s another sign of water-deprived grass. When you see any of these signs, water the stressed area right away, regardless of your normal watering schedule.

How much to water?

Keep in mind that deeper, less frequent watering results in deeper roots and makes more nutrients and water available for your grass to grow and thrive. Since soil dries from the surface down, grass with deeper roots is more drought resistant. Deeper watering also helps dissuade many weeds, especially crabgrass.

To encourage deeper roots, the UGA extension office recommends soaking your lawn to a depth of six to eight inches. The amount of water needed to reach six to eight inches will depend on the output of your sprinkler as well as the type of soil in your yard. Sandy soil may reach that depth with only a half inch of water, whereas a clay yard may need as much as 1.75 inches.

To test the depth of moisture in your yard, push a spade or stake into the ground two to four hours after watering, and measure how far down the soil is moist. Generally the spade will move more easily in damp soil, so you’ll likely feel when you hit dry dirt. If the earth is dry less than six inches down, increase the watering time.

Watch for run-off. Clay soil needs more time to absorb water. You may need to turn off the sprinkler intermittently to give the water a chance to soak into the ground.

When to water lawn?

According to the University of Georgia (UGA) Extension Service, 50 percent more water is lost to evaporation from wind and heat when watering midday as opposed to watering at night. Temperature and wind speeds are often lowest just before sunrise, making it the optimal time for irrigating.

Research shows that watering at night before the dew forms, or in the morning after the dew has already dried, makes your lawn more susceptible to disease. Water just before sunrise while the grass is wet with dew to deter diseases. Of course the time for sunrise changes continually, so check sunrise times every two or three weeks and adjust your watering timers accordingly.

Thatch, a build-up of dead grass between the green grass blades and the soil, and fertilizer are two additional factors that affect a lawn’s water requirements.