It’s pretty easy to give your lawn or garden more water than it needs, especially if you don’t know how to tell whether your plants are thirsty. But excess watering won’t only kill plants; it will also cause your energy and water bills to shoot up. So, how long should you keep your sprinklers running?
Generally, you can run above-ground sprinklers for 20-30 minutes three times a week to sufficiently water your lawn. Run in-ground sprinklers for about an hour. However, the recommended duration will vary based on the kind of soil, the amount of rainfall received, and the sprinkler’s water output.
In order to keep your plants happy and your energy bills in check, you should be careful about how long you run your sprinklers. Let’s take a closer look at how to determine the proper watering time. We also take a look at the signs of overwatering so that you know when you need to make some changes.
How Long Should You Run Your Sprinklers?
The exact time to run a sprinkler systems depends on a number of things. These include the texture and density of the soil, the age of the grass, the kind of grass, the temperature, and how windy it is. Other important factors include the zone’s size and the kind of sprinkler systems you use (pop-up spray heads or rotor heads).
In general, if you have spray heads, you should only water the lawn for 10 minutes per watering session to keep the lawn lush and green. But if you have a rotor head like this one from Orbit (on Amazon), you can increase the time to 20 minutes per session. And of course, you’ll have to adjust the duration if it rains or if rain is in the forecast. Otherwise, you run the risk of having a soggy and overwatered lawn.
Let’s see how additional factors affect the duration of your watering sessions.
In the summers, the ideal watering settings for your garden depend on the kinds of sprinkler heads used in the system. You might even have various kinds of heads in different zones with different overall outputs.
For instance, if you need to run a rotor head for 20-30 minutes, you’ll need to run a traditional spray head for only 5-10 minutes.
Considering the overall output is also important; otherwise, you can easily overwater the lawn. In general, three watering sessions per week are enough for a typical sprinkler system.
Type of Soil
Different kinds of soils have different saturation rates, which means that the duration of the watering session will also depend on the kind of soil you have. For instance, clay is very dense and reaches the saturation point quicker than looser soil types like loam or sandy soils. In fact, sandy soils can’t retain a lot of water, which is why they need more water and more frequently, too.
The amount of rainfall you receive will also determine the duration and frequency of your watering sessions. Use a rain gauge like this one from La Crosse (on Amazon) to determine the amount of water your garden receives in a week from rain. If there’s around 1-1.5 inches of water in the rain gauge after a week, there’s no need to give additional water to the grass.
Similarly, irrigation in the winter depends on the climate. If you get a good amount of snow, you don’t need to worry about turning on the sprinklers at all. Instead, the snow and irregular winter rainfall should be enough to provide 1-1.5 inches of water weekly during the cold since both cool and warm-season grass are dormant in the winters.
Cool-Season Grass vs. Warm-Season Grass
Cool-season grasses such as perennial ryegrass or Kentucky bluegrass need more water compared to warm-season grasses like bahia and Bermuda grass. Plus, both kinds require more water during the active season than in the dormant season.
For cool-season grasses, the active season is fall and spring while warm-season grasses are active from mid-late spring to early fall. Both kinds are dormant during the winters.
So, for instance, the average weekly water requirement for the Kentucky Bluegrass (cool-season grass) is 1.5-2 inches during the active season and 0.5 inches when it’s dormant. Meanwhile, bermuda grass (warm-season grass) only needs an average of 1-1.25 inches of water per week when it’s active and just ⅛ inch per week when it’s dormant.
It’s important to remember here that in both cases, the depth depends on how frequently you water the grass, the climate where you live, and the kind of soil you have.
How to Determine the Water Output of Your Sprinkler
To determine your sprinkler’s water output, put 6 straight-sided containers of the same shape and size in a watering zone and let the sprinklers run for 20 minutes.
Once the time is up, measure the amount of water present in each container (in inches, using a ruler) and take out the average. Then, multiply this average depth by 3 to take out the inches of water delivered in an hour.
If you want to double-check the output, use the tuna can method: Put two clean, empty tuna cans in two different spots and let the sprinklers run for 15 minutes. Then, use a ruler to measure the depth of water in each can and take out the average of the two.
Signs You’re Overwatering Your Grass
There are clear signs of your lawn being overwatered, and it’s important that you know them so that you can take the proper measures to fix the situation.
If you see depressions in the lawn like a matted, mushy, or soggy imprint on the grass whenever you walk on the lawn, it’s a clear sign you’ve overwatered the lawn. In addition to grass that doesn’t spring back after being pressed, faded and dull lawns are also a sign of overwatering.
Fungus — including mold, patch, blight, and algae — on your lawn is another sign of overwatering since they thrive in high moisture. Root rot is another common disease caused by excessive moisture and entails yellow-brown leaves and grass along with slimy, grayish-brown roots.
When’s the Best Time of Day to Water Your Grass?
The best time to water the lawn, especially during the summers, is early morning, ideally between 4 am and 6 am. If you water the lawn later in the day when the sun is high up in the sky, most of the water will evaporate even before the soil gets a chance to soak it. And if the water doesn’t go to the root, your grass will dry out.
Another benefit of giving water early in the morning is that it’s less windy during that time. The grass will therefore be able to absorb the water. If it’s too windy, the water will be blown away, leading to insufficient water going down to the roots.
During a heatwave, planning your watering schedule can be difficult, especially since the sun can fry the grass if it’s wet. However, getting your sprinkler to run early in the morning will make sure that the grass has sufficient time to adsorb the water before the sun is at its peak.
Plus, you can invest in a digital timer such as this one from Rainpoint (on Amazon) and set it to run in the early morning hours automatically. This way, your plants will get the required amount of water even if you’re not free at that time.
However, if it’s impossible to give water to your lawn in the morning, the next best time is from 4 pm to 6 pm, when the sun starts to go down.
Remember that you should never water the lawn at night because it can lead to fungal growth. The dark and damp conditions at night encourage the growth of harmful fungi, which is why it’s better to not give any water at that time.