Watering basics

Improper watering is the culprit behind many lawn problems, especially in the West where healthy grass depends almost entirely on sprinklers. Too little can encourage crabgrass and other weeds that thrive in dry soil. Too much can invite diseases and is wasteful, especially where water is scarce.

Hint

Before planting grass, add compost or other soil amendment to the soil to improve its ability to hold water (see Planting a new lawn for more tips).

How much water

Most lawn grasses need roughly 1 inch of water per week through the growing season. Lawns may need little supplemental water in the humid Southeast or rainy North. But you’ll need that extra 1 inch per week of watering if you live in the Southwest where humidity is low and summer drought is common. Also remember that any lawn needs more water after a hot, dry week than it will after a cool, humid week.

Cut your grass higher during hot spells. Taller grass shoots provide better shade for the soil beneath and require less water. Taller grass also has longer roots which can absorb more water deeper in the ground.

Rain gauges are the most precise way to see how much water your lawn is getting. Place them where they’re exposed to both sprinklers and rainfall. Use several gauges around each sprinkler, then run the sprinklers for 10 minutes. If the water in the gauges measures one-quarter inch, for example, it will take 40 minutes to apply 1 inch of water. You can also measure how quickly your sprinklers apply water by setting empty soup cans around them and then measuring the water inside the cans.

In rainy areas, have a portable sprinkler and hose in case of drought. Use a timer (about $25) or automatic shutoff to manage watering efficiently. For drier climes, you’ll save time and money with an automated underground sprinkler. Maximize these systems’ efficiency by using moisture and rain sensors to override an automated program.

Avoid waste by keeping water off sidewalks, driveways, and other non-lawn areas. Use sprinklers that apply water no faster than the soil can absorb it. Different soils absorb water at different rates; sandy soils absorb it quickly, clay soils slowly. You’ll know it’s time to stop when water runs off the lawn. Choose sprinklers or sprinkler heads that are matched to your soil.

Hint

If your sprinklers apply water too fast, water only to the point of runoff and then stop. Wait about 20 minutes before turning the sprinklers on again.

How often to water

Water only when you must and then water thoroughly. Roots will grow only as deep as the soil is moist, and deep roots make grass hardier and more resilient. Deep but infrequent watering also discourages pests and disease by letting the lawn dry thoroughly between waterings. That works out to once or twice weekly through the growing season in the West and other areas where grass requires watering.

Dial in extra water if you see signs of drought. Persistent footprints are the major one for all regions, indicating that grass blades are losing resilience. Most lawns also have one area that dries out first. Watch that area closely, using it as an indicator for the entire lawn.

Why morning is best

Use sprinklers in the early morning when there’s less wind to blow the water and less sunlight to evaporate it. Morning watering also discourages pests and disease by giving the lawn the rest of the day to dry.

Water sensors can improve the efficiency of in-ground sprinkler systems. The EPA's WaterSense program includes more than 300 certified landscape professionals nationwide who can design efficient irrigation systems or perform efficiency audits on existing systems. To learn more, go to www.epa.gov/watersense.