Temperatures are rising. The rainy season is over, or yet to begin. It’s now up to you to keep your lawn happy and healthy with regular irrigation. But how much water should you be giving your grass? And how can you keep your water bill low?
You should water your lawn in the summer deeply every 3 days for warm-season grasses, and for cool-season grasses, lightly every 3 days for sandy soil, and deeply every 1 – 2 weeks for loam and clay. Track rainfall and adjust the amount of water accordingly. You can also let cool-season grasses go dormant and water them only once every two or three weeks.
What Time of Day Should I Water the Lawn in the Summer?
The best time of day to water your lawn during the summer is in the early morning, when the water can sink deep into the soil. The worst time to water is during the heat of the day, when the sun will evaporate the water before the grass has time to drink. Misting throughout the day has no benefit.
You could also water in the evening instead, but this comes with added challenges. Lawns left wet overnight are more vulnerable to fungi and diseases. Watering after the heat of the day can also “lock in” the heat in the soil [PDF], stressing the roots.
However, if your grass is wilting, then water immediately, whatever time of day it is. If you wait until an optimal time, your grass may die.
How Much Water Does My Lawn Need?
When grass isn’t dormant, most lawns typically need 1 to 1.5 inches of water per week, whether from irrigation or from rain. When lawns are dormant, like cool-season grasses in the summer, they only need ½-inch of water per month. (That’s one way to save on the water bill!)
Some grasses are more drought-tolerant than others. You may not even need to water buffalo grass and zoysia grass, making them superb choices in areas with frequent drought and water restrictions.
As well, grass with deeper roots have more access to water reserves in the soil, so you don’t need to water them as much. In fact, watering less frequently but deeper will encourage your grass to grow its roots deep, and your grass will be more resilient, even through droughts.
To see if your lawn needs watering, just take a walk across the grass. When you look back, if you can still see your footprints, then it’s time to water.
Wondering whether you should mow before or after a rain? We’ve got you covered.
How Do You Tell How Many Inches Of Water Have Been Added?
You can tell how many inches of water your lawn has received through these three methods:
- Set Tupperware containers or empty cans around the lawn. When you turn on the sprinklers, time how long it takes for the water to fill up the container to the required height. That’s how long you should water your lawn.
- Install a rainwater gauge near your lawn. (Pick one with a ruler right in the gauge.) After a rain, write down how much water is in the gauge. However many inches are in the gauge is how many ended up on your lawn. Adjust your watering schedule accordingly.
- Stick a stick into the ground, like you’re checking oil levels in your car. When you pull the stick up, the stick will be wet where the soil was moist.
Also, if there are puddles on your lawn, that’s definitely too much water.
Does Sandy Soil Mean I Have To Water More?
No, sandy soil does not require more water than loamy or clay soils. That’s a myth. Grass requires the same amount of water to thrive no matter what soil it grows in. But since sandy soil holds less water in reserve than loam, you need to water with smaller amounts more frequently.
So, if your loam-having neighbors water four-inches deep every eight days, you need to water one inch every two or three days.
How Do You Keep A Cool-Season Grass Green In The Summer?
A regular irrigation schedule will keep cool-season grass green even during the heat of the summer. You may need to apply more water each time without the help of rain. The best schedule depends on your type of soil — sandy soil requires shallower, more frequent waterings, while loam and clay soils benefit from deeper, less frequent waterings.
But you can always let cool-season grass go dormant. It’s fine. It evolved to do this to survive high heat and low water. Wanting to keep grass green through summer is more of a societal expectation than anything else. If you’re in an area with frequent restrictions on watering the lawn, you might as well learn to let it go and spend your time and energy on more enjoyable activities.
Should You Water Grass Every Day When It’s Hot?
No, there’s no advantage to watering grass every day during a heatwave, and in fact, you could be opening up your grass to further stress, fungi, and disease. The added water will raise the humidity, and like people, grass has a harder time cooling itself down in high humidity. Misting grass throughout the day does not cool down the grass, and usually just results in disease and weed outbreaks.
The best thing to do during a heatwave is to water according to your normal schedule. You can even let cool-season grasses go dormant (brown). Dormant grass requires a lot less water, and when temperatures cool again in the autumn, it’ll turn green again.
Does Having a New Lawn Change My Watering Schedule?
Yes, when you seed a new lawn or install sod, you need to change your watering schedule. The soil of a newly seeded lawn needs to be kept consistently moist but not soggy, requiring daily or twice-daily mistings. Once they’ve germinated, you need to keep the top 2 inches of soil moist until the grass grows 3 inches tall. After that, start pulling back on frequency to encourage the grass to grow deep roots.
Ideally, you’ve installed a new lawn around Labour Day, after the summer heat has passed, giving the new lawn the whole autumn and spring to establish itself before facing a new scorching summer.
If you’ve seeded in spring, you may need to keep irrigating the lawn throughout the summer as the lawn establishes itself. It may not be strong enough to survive the heat without that extra water.
Avoid seeding or sodding new lawns during the summer.
Dangers of Over Watering Lawn in Summer Months
It’s never a good idea to overwater your lawn, whether in the summer or any other time. When you over water your lawn, not only are you increasing your water bills unnecessarily (if you have any), but soggy lawns are more susceptible to fungi and root rot. Mosquitos can lay their eggs in the damp grass.
For how often to water your grass, first ask yourself — can you be okay with letting the grass go dormant? When you’re in an area with frequent droughts and water restrictions, being okay with dormant grass will save you a lot of grief.
And if you choose to irrigate, use this general rule of thumb: water frequently but shallowly for sandy soil, and less frequently and deeply for loam and clay.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.