Watering Lawn 101: Everything You Need to Know

Everyone’s obsessed with hydration these days, but please don’t apply the same preoccupation
to your lawn. In fact, turf research has found that watering every day creates shallow-rooted plants that are vulnerable to drought.

A team of turf scientists at the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) recommends irrigating less often but more deeply, which promotes deep-rooted plants and a healthy turf. Figuring out just how much water to apply and how often depends on where you live and what kind of grass you have.

Keep these variables and tips in mind.

Geography

The Southwest U.S. receives far less rain and gets higher temperatures than, say, the Northeast. So your best bet is to keep tabs on local weather, pay attention to forecasted rainfall, and survey your lawn during the week for signs of dehydration. Use your best judgment. 

Season

Water requirements are lower in the spring, when you may never have to irrigate, and fall, when plant growth slows. Summer is generally prime time for watering—except for cool-season grasses like fescues and bluegrass, which naturally go dormant in the hottest months.

Soil Types

At full water capacity, lighter sandy loam soils contain 2.4 inches of water per foot compared to 4.2 inches in heavier soils, such as silt loam. If your grass thrives in lighter soils, like fescue grass, you may have to water more often. As a rule of thumb, irrigate so that the soil is wet 4 to 6 inches deep. For light, sandy soils, this will take applying ½ to 1 inch of water. For clay-based, heavy soils, apply 1 to 1½ inches of water. To learn more about your soil, check out our article here.

If you want a more precise determination of how much water is in your soil profile, purchase a soil probe. Get a hand tool that removes a soil core for you to examine or an electric probe that provides an instant reading of soil moisture content when inserted in the ground. Another method is to use a spade, dig down six inches or more, and examine the soil for moisture.

Fertilizer Considerations

If your soil is very fertile, grass requires less water to maintain. A well-fertilized lawn keeps thirsty, water-hogging weeds at bay. Fertilize according to recommendations and spread out your applications over three or four times during the growing season.

How Often to Water Lawn

The one type of grass you absolutely should water every day is newly seeded grass. It should be watered lightly at least four times daily. This encourages seeds to germinate and put down roots. Keep seeds moist during the establishment phase with light and frequent irrigation cycles, says Tyler Carr, a turf specialist at Ohio State University. Once your grass seed begins producing new blades, reduce the frequency of irrigation while you increase the depth like you would for more mature grass. Learn more about watering new seedlings by going to Ohio State’s Turfgrass Establishment Series.

Best Time to Water Lawn

Early morning, hands down. Watering at this time allows your grass to absorb the water throughout the day, plumping up blades, which gives them the armor they need to endure the heat of the day. Also, there’s usually less wind in the morning, which affects the uniformity of sprinkler nozzles and can also cause rapid evaporation. An alternative is to water in the late afternoon or early evening. Just be sure to give your turf time to dry out before dark, as letting moisture linger overnight could lead to fungal diseases.

Conduct a Lawn Water Sprinkler Audit

OK, so this may sound a little obsessive, but turf experts recommend conducting an assessment at some point.  Wait … audit my sprinkler? Yes, otherwise how will you know how much water is being doled out? To conduct a quick study, set three or more flat-bottom cans at various locations on the lawn at least 4 feet from (but within range of) the sprinkler heads. Turn on the water for 15 minutes. Using a ruler, measure the depth of water in each can. Averaging these measurements gives you an applied amount. 

Additional Watering Tips

If you want to enhance your irrigation efforts even more, consider the following:

• Mowing Height. Mow at the height recommended by your lawn’s grass species. Bluegrass,for example, should be mowed lower than tall fescue. Mow frequently enough so you never remove more than one-third of the grass height at one time. This promotes deep roots, moisture retention, and weed resistant lawns. 
• Aeration. Taking the time to aerate at least once per year promotes water and nutrient (primarily phosphorus and potassium) uptake by the soil. Find out of your lawn needs to be aerated here.
• Clippings. Don’t bag up your grass clippings. They can provide a natural mulch to slow down evaporation and provide some nutrients to the soil.
• Dethatching. You might need to dethatch a lawn if its layer of plant debris builds up so thick it prevents water and fertilizer from seeping down into roots (check out our article on lawn care for more about thatch removal).