Short answer
Most lawns need about 1 to 1.5 inches of water a week in summer, rain included. Give it in two or three deep waterings, not a little every day. Water early in the morning, before 10 a.m., so less is lost to heat and wind. To find your run time, set out a few empty tuna cans, run one zone for 15 minutes and measure the water in them.
How much and when to water your lawn in the heat
1Midday watering mostly steams away
In the afternoon sun, much of the spray evaporates or blows away before it soaks in. The lawn stays thirsty and the bill climbs.
Read all the steps
- Midday watering mostly steams away. In the afternoon sun, much of the spray evaporates or blows away before it soaks in. The lawn stays thirsty and the bill climbs.
- Water early, before 10 a.m.. Mornings are cooler and calmer, so more water reaches the roots. The grass also dries off during the day, which keeps fungus away.
- Measure with tuna cans. Set three or four empty cans around one zone and run it for 15 minutes. Measure the water with a ruler and work out how long half an inch takes.
- Two or three deep soaks a week. Aim for about 1 to 1.5 inches a week in summer, rain included. Split it into two or three waterings on your allowed days.
- Make sure water reaches 6 inches down. The next day, a long screwdriver should slide about 6 inches into the soil. Deep water grows deep roots, and deep roots handle the heat better.
- Still not fixed? Call a landscaper Especially if: some areas stay dry no matter how long the zone runs (a coverage problem).
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What not to do
- Do not water a little every day. Short runs keep roots near the surface, where the soil bakes first.
- Do not water in the evening. Grass that stays wet all night is an open door for fungus.
- Do not let water run down the sidewalk or the street. Split long runs into two or three shorter ones, 30 to 60 minutes apart, so the water soaks in.
Tips for desert heat
The EPA’s WaterSense program warns that a lot of outdoor water is lost to evaporation, wind and runoff when you water at the wrong time or too long. In Arizona, New Mexico and West Texas, water early, check your heads every month and follow your city’s watering days. Many local water utilities post a weekly watering number for your area in summer.
When to call a landscaper
- Some areas stay dry no matter how long the zone runs (a coverage problem).
- Water runs off before the lawn has had half an inch.
- One zone puts out much more or much less water than the others.
- You want a smart controller set up for your grass, your soil and your watering days.
Frequently asked questions
How long should I water my lawn in summer?
It depends on your sprinklers. Spray heads put water down several times faster than rotors, so times vary a lot. The tuna can test tells you exactly how long your zones take to put down half an inch.
Is it better to water grass in the morning or at night?
In the morning, before 10 a.m. Less water evaporates, and the grass dries during the day. Watering at night keeps the blades wet for hours, which helps fungus grow.
Should I water my lawn every day when it is hot?
No. Water deeply two or three times a week instead. Daily short waterings keep roots shallow, and shallow roots dry out faster in the heat.
How do I know if my lawn is getting enough water?
Push a long screwdriver into the soil the day after watering. If it slides in about 6 inches, the water reached the roots. Grass that stays flat after you walk on it is thirsty.
How much water does a lawn need per week?
About 1 to 1.5 inches in summer, counting rain. In very hot, dry places some lawns need a bit more. Your local water utility may post a weekly number.
Sources
Checked October 24, 2026. Requirements and recommendations change: confirm them on the source site.