How Much to Water Your Lawn (and the Best Time to Do It)
Most lawns need about an inch of water a week, rain included. Learn how to measure it, why deep and infrequent watering wins, and when to water.
Watering is where most lawns go wrong, in both directions. Too little and the grass goes dormant. Too much, or too often, and you get shallow roots, fungus and wasted water. The good news: a few simple rules cover most yards.
The short answer
- Amount: Around 1 inch of water per week for most established lawns during the growing season, counting rainfall. Hot, sandy or windy sites may need more; cool weather and clay soil need less.
- Frequency: Deep and infrequent. One or two long sessions a week beats a short sprinkle every day.
- Timing: Early morning, roughly before 10 a.m.
Why deep and infrequent works
Grass roots grow where the water is. Daily light watering keeps moisture in the top inch of soil, so roots stay shallow and the lawn wilts the moment you skip a day. Soaking the soil 4 to 6 inches deep and then letting the surface dry out pushes roots deeper, which makes the lawn far more tolerant of heat and drought.
If water starts running off before it soaks in (common on clay or slopes), split the session: water until it starts to pool, wait 30 to 60 minutes, then finish.
Count the rain
An inch per week is a total, not an addition. If it rained half an inch on Monday, you only need to add about half an inch. A cheap rain gauge on a fence post, or the observed rainfall for your area, keeps you from watering a lawn that is already wet. Use what actually fell, not what the forecast promised.
How to measure what your sprinkler puts down
Sprinklers vary a lot, so time-based advice like “20 minutes” is meaningless until you measure.
- Place a few straight-sided containers (tuna cans work well) around the area a sprinkler covers.
- Run the sprinkler for 15 minutes.
- Measure the water depth in each can and average it.
- Scale up. If you collected a quarter inch in 15 minutes, you need about an hour for a full inch.
Uneven readings between cans tell you the coverage is patchy, which often explains dry spots.
Why early morning is best
- Less water is lost to evaporation and wind than at midday.
- Grass blades dry quickly once the sun is up, which lowers the risk of fungal disease.
- Water pressure is often better.
Evening watering is the second-worst choice after midday: the grass stays wet all night, and long periods of leaf wetness are exactly what many lawn diseases need.
Signs you are watering wrong
Underwatering: Grass turns blue-gray, blades fold or curl, and footprints stay visible for a long time.
Overwatering: Soggy or squishy turf, mushrooms, more weeds like nutsedge, a spongy layer of thatch, and recurring fungal patches. If you see circular brown patches in humid weather, cut back before adding more water.
Adjust for your grass and season
Warm-season grasses like Bermuda and Zoysia are generally more drought tolerant than cool-season grasses like Kentucky bluegrass, and both need far less water when they are dormant. Not sure which you have? Our guide to cool-season vs warm-season grass will help.
New seed and sod are the exception to “deep and infrequent”: they need the surface kept consistently moist, often with light watering once or twice a day, until roots establish. Then transition gradually to the deeper schedule.