In general, it’s recommended to run your sprinklers two or three times a week and give your grass one-half inch of water each time. Each system delivers water at a different rate, but this is typically about 30 to 45 minutes per zone.
When using a sprinkler system, you want to be as efficient as possible and use water judiciously. You want to give your grass enough water to meet its needs without overeating and being wasteful.
To figure out how long to water grass, you must first determine how long your sprinkler heads take to distribute one-half or one inch of water. Then, you can calculate how long to run them to give your grass its recommended weekly amount when you’re watering two to three times a week.
Determining How Much You’re Watering
The best method is to go outside and measure the amount of water your lawn gets when the sprinkler system is running.
Place empty soup or soda cans on the lawn in a few places where they won’t get tipped over by the sprinkler’s spray. You can run the sprinkler zone until there is half an inch of water in the container, or you can run the zone for 30 minutes and measure how much water collects.
If there’s more than half an inch, you know you can run the zone for less time; if there’s less than a half inch, you’ll need to run that zone longer. You can either adjust the system times over the next few waterings or do some math and extrapolate how long it should take to get an inch of water.
Repeat this process for each zone.
Note: You can also measure to one inch instead of the half inch. Both measurements should yield the same results in the end.
Recommended Watering Amounts For Grass Types
The amount of water your grass needs may vary depending on your grass and your local climate.
On average, most turfgrasses need about 1” of water a week for optimal growth. This amount may increase a bit when it’s unseasonably hot and dry, especially for cool-season turf types.
- Kentucky bluegrass: 1” per week
- Perennial ryegrass: 1” per week
- Tall fescue: 1” per week
- Fine fescue: 1” per week
- St. Augustine: 1.25” per week
- Bahiagrass: 1” per week
- Bermuda: 1” per week
- Zoysia grass: 0.75” per week
- Centipedegrass: 1” per week
How Many Times a Week to Water
A common misconception with your lawn is that you should water it every day. This practice is not the case. Soak the ground sufficiently two or three times a week instead of sprinkling a little bit daily.
When you water every day, your grass develops shallow roots that need to guzzle water daily to stay green. The grass has little drought tolerance and will struggle without water in as little as a few days. Especially when it’s hot.
Instead, you want to give your grass more water less frequently. Watering this way encourages the roots to grow deeper in search of moisture. In turn, the grass has a more extensive root system, providing more access to water and making the grass more drought tolerant.
Determining How Long to Water Grass Each Time
Knowing how long it takes to get a half inch or inch of water and the amount of water your grass needs each week, you can figure out how long to run each zone.
For instance, it takes 20 minutes to emit one-half inch of water, and your Kentucky bluegrass needs 1” of water a week. Therefore, you’ll water your lawn for 20 minutes twice a week to give it the recommended amounts.
If it takes 50 minutes to emit 1” of water, you’d need to water twice a week for 25 minutes each time.
Should You Adjust Watering Frequency and Amounts?
Your lawn’s watering needs change throughout the growing season in response to the temperatures.
Cool-season grasses aren’t as heat tolerant as warm-season so they need extra irrigation in the summer to keep them from going brown. But they can get by with less when it’s cooler in the spring and fall and don’t need any water when they’re dormant in winter.
Warm-season grasses are adapted to hot summer temperatures, so they typically don’t need extra water when it’s hot—only during extended drought periods. Unlike cool-season grasses, warm-season types need occasional watering during the winter to keep them from drying out and suffering from winterkill.
Some people like to adjust seasonally to increase their water use efficiency. An Irrigreen smart irrigation controller will monitor the weather and regularly make adjustments once you set the base watering time.