'Cutting grass in hot weather can do more damage than good' – expert mowing tips for high temperatures (2024)

Cutting grass in hot weather is a chancy business and runs the risk of causing long term lawn damage.

While it may seem tempting to mow when the weather is dry, experts say it can lead to unsightly brown patches appearing and – even worse – complete die back. Both of which take a great deal of time, money, effort and patience to repair.

If the weather is hot, chances are your lawn is already under stress, no matter how carefully maintained it is, so deciding to reduce its height by a third or even half is not the greatest idea. Knowing more about how grass grows and good general lawn care is key to deciding when to mow for the best results, so we asked lawn care professionals to share their advice.

'Cutting grass in hot weather can do more damage than good' – expert mowing tips for high temperatures (1)

(Image credit: Getty Images/Tim Parnell)

How hot is too hot to mow the lawn?

‘Lawn grass or turf has some basic rules that apply whether it is a cool season or warm season grass,’ says Stacie Smith, owner of landscaping specialists Smithson Exteriors. ‘There isn't an exact temperature limit for cutting grass in hot weather, but when there are sustained temperatures above 90˚F, turf struggles to retain the moisture that it needs, especially when there is a lack of rainfall.’

Some grass varieties suffer more than others, advises Stacie. ‘Cold weather grasses like Kentucky bluegrass, perennial ryegrass, and fescues especially suffer from heat stress when temperatures are high, and rainfall is low. If the temperature is high buttherehas been sufficient rainfall, it is unlikely any damage will occur whenmowing. However, if there is a lack of rainfall andhigh temperatures, mowing cancause more damage than good.’ Bear all of this in mind when considering how often to mow your lawn during hot, dry spells.

Mowing new lawns in hot weather

You might also be wondering if the mowing advice for hot weather differs depending on how established (or not) the lawn is.In short, it does make a considerable difference and here’s why.

‘Turf that is well established has a much thicker rootbed and canhandle high temperatures and low moisture much better than newlyplanted turf,’ says Stacie Smith. ‘This root bed can be 4in to 2 feet thick and it will hold the moisture from previous rainfall for a much longer period of time than newly planted turf can.’

Gene Caballero, co-founder of GreenPal agrees and says, ‘If yourlawnis new, it is more susceptible to damage from mowing in hot weather. For a newlawn, it is best to avoid mowing it when the temperature is above 70˚F.’

Even if you've planted fast-growing grass seed and your lawn looks like it is growing well on the surface, chances are the roots will still be fairly shallow, so don't risk causing any longterm damage.

'Cutting grass in hot weather can do more damage than good' – expert mowing tips for high temperatures (2)

(Image credit: MariuszBlach/Getty Images)

Potential problems

Scalping the lawn in hot weather is never a good move as it can result in you having to repair bare patches in grass and can leave other areas to quickly turn brown.

‘Damage to the turf can occur when the stems of lawn grass are cut too short and cannot shade the lower portions of the turf,’ says Stacie Smith. ‘Dull blades on lawn mowers can cause greater damage on a dry lawn and expose the grass to disease. Most turfs that experience heat stress can be restored with proper watering and maintenance. Even if a lawn looks very dry and brown, with a few good rains it can come right back to life.’

Precautions to take when cutting grass in hot weather

Occasionally the urge to restore order and a neatly cut lawn is too great to ignore, no matter what the weather. If you find yourself contemplating mowing in hot temperatures be sure to follow this professional advice.

‘If you really do have to mow or tidy up yourlawnin hot weather, there are a few things you can do to minimize the damage,’ continues Gene. ‘First, try to mow when the temperatures are cooler, such as in the early morning or late evening. Second, raise the height of the blades on your lawn mower. This will help to reduce stress on the grass blades. Third, water yourgrassthoroughly after mowing. This will help to cool the grass and prevent it from wilting.’

Types of lawn grass to avoid mowing when it’s hot

Knowing your lawn’s grass type can play an important role when maintaining a healthy lawn. Each type of grass will have different growing habits and some might be considered to be a more drought-tolerant grass than others.

As a result of this, there are some grasses that are more sensitive as to when they are cut. Gene Caballero highlights some of those that you should certainly avoid mowing in extreme heat as they can be even more susceptible to damage.

  • Kentucky bluegrass is a cool-season grass. It can tolerate heat up to 85˚F, but it will start to wilt and die if the temperatures get much higher.
  • Annual ryegrass is another cool-season grass that is not as heat-tolerant as warm-season grasses. It can withstand temperatures up to 90˚F.
  • Fine fescue will start to wilt and die if it does not get enough water and temperatures exceed 95˚F.
  • Creeping bentgrass is another cool-season grass that can cope with temperatures upto 85˚F.

FAQs

Should you mow in high temperatures?

‘As a general guideline, you want to avoid mowing your lawn in temperatures above 90°F,’ says Ryan Farley, CEO of Lawn Starter. ‘When it's excessively hot, the grass is already under stress due to heat and potential dehydration. Mowing can exacerbate this stress and potentially damage your lawn.’

How long will the lawn take to recover from mowing in hot weather?

Lawn recovery time really depends on the type of grass, the soil condition and the severity of the heat. Following a good dose of rain or heavy watering it usually takes around a week for the grass to green up, but if your soil is particularly free draining or your lawn in generally poor condition it can take twice as long.

Just as cutting wet grass can cause problems for your lawn, so too can mowing in excessive heat.

To give your lawn the best chance of growing green and thick, it's best to wait for temperatures to reduce so you don't cause undue stress to your turf.

'Cutting grass in hot weather can do more damage than good' – expert mowing tips for high temperatures (2024)

FAQs

'Cutting grass in hot weather can do more damage than good' – expert mowing tips for high temperatures? ›

'As a general guideline, you want to avoid mowing your lawn in temperatures above 90°F,' says Ryan Farley, CEO of Lawn Starter. 'When it's excessively hot, the grass is already under stress due to heat and potential dehydration. Mowing can exacerbate this stress and potentially damage your lawn. '

Is it bad to mow the lawn when it's hot? ›

Mowing a lawn in the middle of a summer heatwave is one of the worst things you can do to it. When temperatures reach around 85 degrees, grass, like many other green plants, begins to suffer – especially cool-season grasses such as Kentucky bluegrass, perennial ryegrass, and fine fescues.

What temperature should you not mow the lawn at? ›

Although grass does not stop growing in winter, it grows so slowly when temperatures go below 40 degrees Fahrenheit that mowing your lawn between November and March isn't necessary (scroll down to see the step you must follow if you need to mow your lawn during winter).

Should you cut grass when it is 90 degrees? ›

Mowing while it's really hot out stresses out your turf. It can also result in “heat tracking,” which is any damage caused by traffic on heat-stressed turf. “The resultant damage may look like RoundUp was on the tires of the (lawn mower),” says Kevin Frank of the Michigan State University Extension.

Is it safe to mow in 100 degree weather? ›

Don't mow your lawn at 2 in the afternoon when it is 100 degrees out. Your grass is already stressed and doesn't need the added stress of a mow. Wait until dusk when the sun is going down and it starts cooling down. ...

What temperature is too hot for grass? ›

Once temperatures reach 77 degrees, it becomes too hot for root growth, and root growth ceases. When temperatures reach 90 degrees, it becomes too hot for shoot growth and the grasses stop growing and begin to fall dormant, with the surface grass turning a brown hue.

Is 80 too hot to mow? ›

Once your grass has come out of its dormant state, you may be wondering when you should start cutting it again. Generally speaking, if it is below 50 degrees Fahrenheit, it is still considered to be too cold to mow your lawn. The ideal temperatures to mow are between 50 to 80 degrees Fahrenheit.

What length should grass be cut in hot weather? ›

A mowing height between 2.5 to 3 inches is best for most of the season, except during summer stresses when the lawn mowing height should be raised one-half inch to mow at 3 to 3.5 inches. Raising the mowing height provides more insulation from summer heat and reduces water loss from your soil.

Does frequent mowing thicken grass? ›

Mow Properly

Using best practices for mowing helps your grass grow thick and stay that way. Rather than mowing based on your weekly calendar, mow according to grass needs. Mow often enough to maintain your grass type at its recommended mowing height without removing more than one-third of the height in a single mowing.

What time should you not mow? ›

However, be mindful that mowing too close to nightfall (between 6 and 8 p.m.) will not give your grass enough time to recover, making your lawn more susceptible to fungus and turf disease. It's recommended to avoid cutting your grass in the early morning and midday.

How often should you water your lawn in 90 degree heat? ›

In general during hot summer months, you should be watering your lawn up to three times per week if there wasn't any recent rainfall. As a general rule of thumb, watering up to one inch deep each time you water your lawn is ideal.

Why shouldn't you mow your lawn every week? ›

Mowing every two weeks — instead of weekly — and not dousing grass with chemical herbicides and fertilizers, helps the environment and supports the health of bees, which are among the world's most important pollinators.

Is 90 degrees too hot to fertilize lawn? ›

The best time to fertilize your lawn is when the grass is actively growing, and for cool-season grasses, that's when temperatures are 60 to 70 degrees F. For warm-season grasses, active growth will usually happen when temperatures are between 75 and 85 degrees F.

Is it bad to cut grass when its really hot? ›

If the temperature is high but there has been sufficient rainfall, it is unlikely any damage will occur when mowing. However, if there is a lack of rainfall and high temperatures, mowing can cause more damage than good. ' Bear all of this in mind when considering how often to mow your lawn during hot, dry spells.

What temperature should you not mow? ›

Depending on the climate where you live and the species of your grass, the growth of your grass will either significantly slow down or go into dormancy during the cold winter months. You should never mow your lawn when temperatures are below freezing point or consistently below 40 degrees Fahrenheit.

What grass is good for 100 degree heat? ›

Heat Tolerance

Bermudagrass is extremely heat tolerant — daytime temperatures of 95 to 100 degrees Fahrenheit are optimal. Pennington Bermudagrass yields dense, resilient, heat-tolerant lawns. Zoysia grass, Centipede grass and Bahiagrass also tolerate high heat very well.

When not to cut grass? ›

Never mow wet or frosty grass

This can damage your turf and compact the soil. Wait until later in the day when the lawn has dried out or defrosted, or postpone mowing to another day.

How do you mow in extreme heat? ›

TIP: For mowing in the heat of summer, follow the one-third rule but let your grass grow roughly . 5 of an inch higher than the recommended cutting height. Never remove more than one-third of your grass height at one time because this will lead to more stress, potential scalping of the lawn and/or disease.

What is the best time to mow a lawn? ›

Mid morning or late afternoon is usually the best time to mow the lawn. If done too early in the morning the lawn will be damp with dew which can cause the grass to tear rather than cut cleanly, leading to disease. Midday can be too hot, the intense sun can stress the newly cut grass but it is not too bad a time.

Is it bad to water grass when it's really hot? ›

The dangers of watering your grass in hot weather

Shallow root growth: Watering your grass at the wrong time in hot weather is an easy way to damage it. Don't irrigate between 10 a.m. and about 4 p.m., as most of the water will evaporate instantly without benefitting your lawn.

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