Learning Center / Lawn care basics
How much should you water your lawn?
An established fescue lawn needs about an inch of water a week, rain included, applied in one or two deep soakings early in the morning. New seed is the exception: it needs light, frequent watering for two to three weeks.
- By David Obeid, founder
- Reviewed
- 5 min read
The short answer
How much water does a lawn need each week?
About an inch a week, counting rain, for an established tall fescue lawn in the growing season. If it rained half an inch this week, you only need to add about half an inch.
How you apply it matters as much as how much. One or two deep waterings push roots down into the soil, where they stay cooler and find moisture longer. A light sprinkle every evening keeps the roots shallow and the grass wet overnight, which invites disease.
Measuring it
How do you know how much your sprinkler puts down?
Most people guess, and most guesses are off. This takes one watering to figure out.
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Set out a few straight-sided cans
Empty tuna or cat food cans work well. Spread several across the area one sprinkler zone covers.
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Run the zone for 20 minutes
Then measure the water in each can with a ruler.
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Do the math once
If the cans average a quarter inch in 20 minutes, it takes about 40 minutes to put down half an inch.
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Look for uneven cans
If some cans are nearly empty while others are full, the coverage is uneven, and the dry spots in your lawn may be a sprinkler problem, not a grass problem.
Timing
What time of day should you water?
Early morning is best. Less water is lost to heat and wind, and the grass dries off during the day.
Evening watering leaves the lawn wet all night, and long wet stretches in warm weather are exactly what lawn diseases like brown patch need. Midday watering works, but more of it evaporates before it soaks in.
Clay soil
Why does water run off instead of soaking in?
Usually because the clay soil common across Northern Virginia is compacted and can only take in water so fast. When water puddles or runs down the driveway, split the watering into two shorter runs an hour or so apart so it has time to soak in.
If runoff happens every time, the soil itself is the problem. Fall core aeration pulls plugs out of compacted clay so water, air and roots can move through it again. Here are the signs your lawn is compacted.
New seed
How should you water a newly seeded lawn?
Lightly and often, enough to keep the seed consistently moist for about two to three weeks. This is the opposite of watering an established lawn, and it is the single biggest factor in whether new seed takes.
Seed that dries out after it starts to sprout usually dies, so short waterings once or twice a day beat one long soak. Once the new grass is up and growing, shift gradually toward deeper, less frequent watering. After aeration and overseeding, we walk every client through exactly how to water their new seed.
Related questions
What people also ask
Should I water every day?
Not an established lawn. Daily light watering keeps roots shallow and the grass wet, which invites disease. One or two deep waterings a week, about an inch total including rain, is better. Newly seeded lawns are the exception and need light, frequent watering for two to three weeks.
Is it bad to water at night?
It is the least helpful time. Grass that stays wet overnight in warm weather is more prone to disease. Early morning is best.
Do I need to water after overseeding?
Yes, and it is the single biggest factor in success. New seed needs to stay consistently moist for about two to three weeks to germinate, which usually means light, frequent watering. Lawns with irrigation have an easier time of it.
Should I water before or after a lawn treatment?
It depends on what was applied. We'll let you know what to expect with each visit so you can plan around it.
Keep reading
More from the Learning Center
- What should you do for your lawn each season in Northern Virginia? A season-by-season lawn calendar for tall fescue: what happens in winter, spring, summer and fall, and which season matters most. Timing and seasons · 6 min read
- How do you get rid of lawn weeds and keep them out? Pre-emergent versus post-emergent, why crabgrass timing follows soil temperature, and why a thick lawn is the best weed control there is. Lawn problems · 6 min read
- How can you tell if your lawn is compacted? The warning signs of compacted clay soil, why it happens so often in Northern Virginia, and what actually fixes it. Lawn problems · 4 min read
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