How Long Should You Water Your Grass? Experts Weigh In

A lovely green lawn plays a big part in the overall curb appeal of a home, but keeping that lawn green requires something very important: water. An under-watered lawn is a problem, but an over-watered lawn can cause problems, too. Add in the seasonal fluctuations in water requirements, and it starts to feel quite complicated. We talked to horticulturists for their best advice on how long to water grass, plus their tips for how to keep it looking its best.

How Long to Water Grass By Season

Your lawn will naturally have different watering requirements depending on the time of year and the precipitation patterns in your climate. But don’t go into the process thinking your lawn is particularly fragile. "A commonly held misconception is that lawn grass is shallow rooted and [thus] inferior to any native plant," says Galen Gates, horticulturist and contributor to numerous books on grasses. "That is not true. Bluegrass has a root system that goes 2 feet deep." Gates also notes that, as with any plant, the best watering regimen is an infrequent but deep watering that keeps the roots deep where water will be available for a longer period of time.

So what should your starting point be—how much water per week should be your guideline to adjust throughout the seasons? "For cool-season lawns of Kentucky bluegrass, perennial ryegrass, and fescues, the watering frequency will vary depending on the season," says Aaron Steil, consumer horticulture extension specialist at Iowa State University Extension and Outreach. "Most lawns in [the Midwest] require approximately 1 to 1 ½ inches of water per week."

How Long to Water Grass in Spring

You should aim for ½ to 1 inch of water each week in one or two 30-minute watering sessions. But you want to make sure that you’re not going into the heat of summer with the lawn too conservatively watered. "In spring, [rain] is often provided more readily by Mother Nature and temperatures are cooler so the amount of irrigation that must be done to keep the grass green and healthy is less than in summer,” says Steil.

Remember: Many factors can influence how much water your lawn will receive in those 30 minutes, including "water pressure, hose diameter, or your sprinkler's configuration," says Gates. You can place empty tuna (or other) cans on your lawn as you water and then watch to see how much water they contain after 30 minutes (the average is about ½ inch). Then, adjust your watering as needed to hit the desired sweet spot. Be sure to factor in rain amounts each week to help you decide how much to water.

How Long to Water Grass in Summer

You’ll want to be watchful of dry periods during the summer months. Generally, you should aim for an average of ½ inch of water per 30-minute watering session—and about two or three of these sessions per week. "During extended dry periods, turf grass foliage will go dormant, cease growth, and turn brown," says Steil. "While the foliage is dead, the turf grass crowns and roots remain alive. If you want to maintain a green lawn over the summer months (and not allow it to go dormant), regular irrigation is required. This often means watering with regular frequency to provide that 1 to 1 ½ inches of water per week."

How Long to Water Grass in Fall

Fall may offer cooler temperatures that make it easier for your lawn to retain water. Water requirements in autumn will be similar to spring; aim for a ½ to 1 inch of water each week, in one or two 30-minute watering sessions.

You also can use this season to set your lawn up for the winter season ahead. "In autumn," says Gates, "there should be a reasonable amount of moisture in case of an open (no snow) windswept winter that can desiccate the crowns of the plant."

How Long to Water Grass in Winter

Depending on your location, winter may bring a reduction in liquid moisture—but your lawn is likely dormant and not in need. "During the winter with cooler temperatures and less growth, supplemental irrigation can be reduced," says Teresa Watkins, horticulturist and University of Florida master gardener for 24 years. You may also want to adjust the height of the grass just before winter. In the summer, you’re ideally cutting it at 3 to 3 1⁄2 inches, but Gates suggests that going into winter with cooler temperatures it can be cut lower, "about 1 1⁄2 to 2 1⁄2 inches to guard against diseases," he says.

Signs Your Lawn Needs Water 

You want to be vigilant in watering your grass properly, but what are the signs that your lawn needs water? Here are the signs to watch out for, according to our experts.

• Pale or bluish grass color: Pay attention to the color of your grass, and how it’s responding to the environment. "Is it [a] paler color or bluish? Then irrigate normally," says Watkins.
• Dry soil: Try feeling the soil down an inch or two with your finger. "Dry, sandy, or hot? Irrigate normally," says Watkins.
• Browning or white grass: "When a lawn turns a tan color, it needs water," says Gates. "Bluegrass (the most common lawn grass) can go dormant for a short period of time but not much more than a week or two (after turning tan or light brown). If the grass turns white, it is gone."

Signs You've Overwatered Your Lawn

In all your zeal to care for your grass, it’s possible to overdo it. Too much of a good thing is sometimes a bad idea, and this definitely applies to watering your lawn. "It's important to avoid frequent, light applications of water, which promote shallow rooting and lush growth," says Steil. "Lush, shallow-rooted turf grass is less drought tolerant. If you are irrigating more than once or twice a week, you are likely overwatering. Ideally, you are applying the needed amount of water in a single application or possibly two applications three or four days apart."

A few more ways to determine if your grass is overwatered:

• You can't see your footprints in the grass. "Walk across your lawn, wait one minute, and turn around and look for your footprints," says Watkins. "If you can’t see your footprints in the grass after one minute, no need to irrigate—your turf has enough moisture in the leaves to bounce right back. If you see your footprints, then irrigate normally."
• The soil is wet. "Stick your finger in the ground to your second knuckle. Is the soil cool, moist, or wet? No need to irrigate," says Watkins.  
• The grass is green. "Is your grass nice and green? No need to irrigate," says Watkins. 
• Dollarweed is popping up. "A big indication in the Southeast is the appearance of dollarweed, Hydrocotyle umbellate," says Watkins. "Dollarweed is an aquatic plant that only grows in lakes, along shorelines, low-lying areas, and lawns that are overwatered."
• Grass leaves are yellowing, or are slimy brown. Overwatering can lead to chlorosis, which is the yellowing of the grass blades, indicating bloated roots, notes Watkins. Also watch for "slimy brown leaves indicating rot, wilt, or fungal disease," she says.

Tips to Consider When Watering Your Lawn

Finally, there is no shortage of tricks and tips to help put your lawn in the best condition possible. Here are a few ideas:

Water Early in the Day

"Early morning (5 a.m. to 9 a.m.) is the best time to water a lawn," says Steil. "A morning application allows the water to soak deeply into the soil with little water lost to evaporation. When watering is completed, the turf grass foliage dries quickly."

Young Lawns Need Special Care

Steil notes that newly germinated seedlings have very limited root systems so they easily dry out if not irrigated frequently. "After seeding, you need to keep the upper 1 inch of soil moist with frequent, light applications of water," says Steil, which is somewhat different from what an established lawn requires. "It's often necessary to water newly seeded areas once (maybe even twice) a day," she says.

Don’t Overthink It

"Nature supplies water in the form of seasonal rainfall based on the geographical region," says Watkins. "If you have an established sustainable landscape (right plant, right place, even for turf grass, and best management practices), it often only needs supplemental irrigation when we have extreme drought or as instructed when applying chemicals. Grass is a plant species that does not need as much care as most people think."

Fertilize as Needed

You may need to consider feeding your lawn to give it the best shot at success. "All grass should be given a regular diet of nutrients, primarily nitrogen," says Gates. "Nitrogen should be applied at 4 pounds per 1,000 square feet/year. This includes a fall application." But as you fertilize, realize that the watering needs of your lawn may increase while the grass responds to the feeding. Also, consider a soil test before fertilizing, suggests Watkins.

Grow the Right Grass for Your Climate

Gates notes the importance of adapting your plans to the region. "The Midwest tends to have heavier soils which [are] most applicable to bluegrass and fescues. The South (Kansas and south) and drought areas of the far West and Southwest will benefit from other grasses like Bermudagrass, Zoysia, and Bufalograss," says Gates. Gates says growing temperatures are more extreme in these areas, and the soils tend to have sharper drainage, which requires more moisture.