How to water a lawn
How much, how often and the best time of day
How much
Most lawns do best with about 1 inch (2.5 cm) of water a week, from rain or watering. Hot, dry, windy places can need more, and sandy soil needs watering more often.
An inch of water soaks roughly 6 inches (15 cm) into the soil, right where the roots are.
Deep, not daily
Water deeply but infrequently: give the week's water in one soaking, or two about 3 or 4 days apart. Frequent light sprinkles keep roots shallow.
Watering too often also favors moss, algae and moisture-loving weeds.
Water early
Early morning, roughly 5 to 9 a.m., is the best time. There's less wind and evaporation, and the grass doesn't stay wet for long.
Know when and how much
Your lawn and a few cans will tell you.
- Thirsty grass turns a dull blue-gray, the blades roll inward, and footprints stay pressed in.
- Set a rain gauge or a few straight-sided cans, like tuna cans, in the sprinkler's path, and time how long they take to fill an inch.
- If water starts running off clay soil or slopes, move the sprinkler and come back to finish later.
- Depending on the sprinkler, an inch can take anywhere from 30 to 90 minutes.
Letting it go dormant
Established cool-season lawns can be allowed to go brown and dormant in a summer drought. They can stay dormant for 4 to 6 weeks without much harm.
To keep the crowns and roots alive in a long drought, extension advice varies. One approach is about 0.5 inch (1.3 cm) every few weeks. Another is 1–1.5 inches (2.5–4 cm) after 4 to 6 weeks of dormancy, repeated about every 4 weeks. Keep foot traffic off, and avoid letting the lawn bounce in and out of dormancy.
New seed
Newly seeded lawns are different. Keep the top inch of soil moist with light, frequent watering, often once or twice a day, until the grass is up in 2 to 3 weeks. Don't let a new lawn go dormant.
Sources
- University of Maryland Extension: Maintaining an Established Lawn
- Iowa State University Extension: Watering Home Lawns
- Iowa State University Extension: Summer Dormancy of Cool-Season Lawns
- Purdue University Turfgrass Science: My Lawn is Brown and Crunchy: Is it Dead?
General guidance, not a diagnosis. Written by PlantWiz in our own words from the sources above.