What is Lawn Heat Stress & How to Deal With it? Question Answered!

Most of us love a long, hot summer. Right?

But our lawns? Not so much.

Hot weather without adequate rain can make for a very unhappy lawn. Cue: Heat stress.

Wondering what lawn heat stress is and what to do about it? I’m going to explain!

Key Points

  • Lawn heat stress occurs when your lawn is exposed to prolonged hot and dry conditions.
  • The only real way to remedy it is through a few deep watering sessions.
  • But, there are other things you can do to prevent a heat stressed lawn or to help heat stressed grass recover. These include how you water and mow, and avoiding fertilizing and excess foot traffic while the lawn is stressed.

Contents

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What is Lawn Heat Stress?

You may think your grass is dying from heat.

But actually, heat stress is dehydration in your lawn.

It’s a form of stress that your lawn experiences when it is exposed to heat with inadequate water for a prolonged period of time.

Interestingly, it’s not so much the temperature that causes lawn heat stress, but the length of time that the grass is forced to go without water.

Both cool and warm-season grasses can experience heat stress, but it’s much more common in cool-season grasses that aren’t adapted to drought conditions. Warm-season grasses will last a lot longer than cool-season grasses without water before getting stressed.

Usually, heat stress is what your lawn will experience just before it starts to go dormant, as dormancy is a protective mechanism against damage from heat stress.

green grass and dry dead grass

How to Recognize Heat Stress in Your Lawn

There are a few different things that you can look for when trying to identify heat stress in your lawn.

These are:

  • The overall lawn may appear to have shrunk due to a lack of water. It might look like the edges are pulling away from solid structures like paths or driveways, and cracks may appear through the lawn.
  • The lawn will start to experience some discoloration, usually a slightly darker green, then yellowing, then browning. Discoloration can start at the tips and then slowly the whole blade of grass will turn yellow or pale brown. The lawn can also gradually change color as a whole, or change in patches.
  • If you walk across the lawn and the grass doesn’t spring back into position but stays compacted, this is another sure sign of heat stressed grass.
  • One final way to find out whether your lawn needs a drink is the screwdriver test. As you’ll see later in this article, heat stress can be made worse by compacted soil. But, heat stress can also help to cause compacted soil. If it’s hard to push a screwdriver into your lawn, that may be a sign of heat stress.

Dead Grass

What to do About Heat Stress in Your Lawn

The primary solution to heat stress is water.

Water rehydrates your lawn while also helping to cool soil temperatures, which in turn helps to prevent further evaporation.

However, often heat stressed lawns are so dry that they actually repel water rather than absorb it. This means the best way to water your lawn is actually by doing it in stages.

Start with a light watering on one part of your lawn, wait for it to soak in and then move to the next patch. Once this light watering has been successfully absorbed, you can do a second round and aim for around half an inch of total watering.

It does sound time-consuming, I’ll admit. But don’t worry, your patience will pay off and this careful watering will definitely prevent your lawn from suffering further heat stress.

What Next?

Ok, so it’s been a week and you’re seeing some signs of green. That’s great!

But unfortunately, this isn’t a case of one and done. Your lawn will need more regular watering throughout the remaining dry months to keep it happy.

To maintain the health of your lawn, aim for one or two deep waterings per week.

Any more than this isn’t necessary. Less frequent, deeper watering is actually better for lawn health as it encourages deeper root growth which makes the grass more resilient.

Also, be sure to water early in the morning to avoid encouraging disease and unnecessary water loss through evaporation.

Watering your lawn can sound like a bit of science, right? There are definitely right and wrong ways to do it. But don’t worry, I have all the facts right here in this article to make it easy for you.

lawn being watered in closeup

What if I Have Water Restrictions?

Good point.

If your region is experiencing water shortages and restrictions then you may not be in a position to water your lawn. In this case, you may have to allow it to protect itself by going dormant and then wait for water restrictions to ease and give it a good drink as fall arrives.

And don’t worry, dormancy is a natural process and isn’t harming your lawn (provided it doesn’t persist beyond 6 weeks or so, that is).

Other Things You Should Do

Aside from watering, the other things you should do to look after a heat stressed lawn are actually more about what you shouldn’t do.

If you think about it, your lawn is already stressed, so what you want to do is try and avoid more stress.

Things that can stress a lawn include lots of foot traffic, frequent, short mowing, and use of lots of lawn furniture.

If you can ease off on the mowing and restrict foot traffic then your heat stressed lawn will thank you!

What if I See No Improvement?

The caveat to all this advice is that your lawn may already in fact be dormant.

This is especially likely if you’ve been away on vacation and weren’t present to witness the slow descent into a heat stressed state and then, ultimately, dormancy.

If your lawn is already dormant then the best way to look after it is actually similar to caring for a heat stressed lawn, except you will water a little less. Unfortunately, it won’t return to its lush green state until temperatures drop and an abundance of water arrives with the change of seasons. But fear not, this will happen!

You shouldn’t necessarily try to bring a dormant lawn out of dormancy if you are experiencing drought conditions with limited water available.

This will just create more stress for it. Instead, you’re aiming for the minimum amount of water possible to stop your grass from dying completely. Some recommend around ½ inch, once per week.

a green lawn in backyard

How to Prevent Heat Stress in the Future

There are some things that make a lawn more susceptible to heat stress.

If you can avoid these things and instead do things to promote the health of your lawn, then it should be more resilient come summer, and better able to cope with heat stress.

Compaction

Compaction is a big contributor to heat stress because it limits the amount of water that the roots can access. Making sure your lawn is well aerated prior to summer will help a lot to prevent heat stress.

If you’re new to aeration, no problem! I have a complete guide to aeration here, and a list of different types of aerators to consider here.

On a similar note, dethatching can be just as helpful as aeration in helping your lawn to stay healthy, so add this to your pre-summer lawn care job list!

If you’re a bit overwhelmed by all the different lawn care jobs and when you should do them, I have a lawn care calendar that might be helpful.

Short Mowing

Mowing your lawn too short can also increase a lawn’s susceptibility to heat stress.

Mowing shorter actually means that you end up with shallower roots. Shallower roots can’t reach down into the soil as far to access moisture that might be present deeper in the ground.

This means that when a period of dry weather arrives, your lawn won’t last as long before it starts to get heat stressed.

Instead, mowing longer encourages deeper roots which means your grass has access to more moisture for a little longer.

Are you in the market for a new lawnmower or not sure whether you’re using the right kind for your yard? I have an article dedicated to different lawnmower types that you might find interesting.

person using zero-turn lawnmower

Light Watering

On a similar note, frequent, light watering also leads to shallow root growth.

Instead, less frequent, deep watering encourages deeper root growth and with it, an increased ability to access water.

Avoid Fertilizing

What? Surely fertilizing your lawn is a good thing?

It is, but only at certain times of the year. The general rule of thumb to remember is to only fertilize your lawn during its active growth phase. Fertilizing your lawn when it is not actively growing may do more harm than good.

Not only are cool season grasses not actively growing much during the summer, but if they are heat stressed then fertilizing is actually only going to result in more stress!

Confusing, right?

This is because fertilizer encourages leaf growth at the expense of roots, when what we really need in summer are healthy roots. You can read more about fertilizing know-how and the different types of lawn fertilizers here!

Summary

Heat stress is not something we want our lawns to have to put up with. But luckily there are things we can do to help a heat stressed lawn once we’ve identified it.

If your lawn is discolored, appearing to shrink, and footsteps stay visible on the grass after you’ve walked across it, your lawn may be experiencing grass heat stress.

Remedying lawn heat stress is fairly simple provided you have access to water and your lawn was healthy to start with. Carrying out basic lawn care jobs throughout the year can help ensure your lawn is as healthy and resilient as possible when the stressful months come!

Make sure you have the right yard care tools on hand. Some things like expandable garden hoses can make your life a lot easier so they’re worth checking out!

Did you find this article helpful? I’d love to hear your thoughts!

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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