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What Temperature Is Too Hot To Mow The Lawn?

green park view What Temperature Is Too Hot To Mow The Lawn?

Your lawn is getting a little too long. But you can fry an egg on the sidewalk. Is it really smart to mow the grass? Or better to have a beer and wait? 

If the hot weather lasts long enough, the grass will go dormant. You won’t have to cut it. It is also better to leave the grass longer in hot weather.

We’ll help you manage a stressed lawn when the weather is hot. 

man cutting grass with lawn mover back yard What Temperature Is Too Hot To Mow The Lawn?
Mowing a healthy lawn

What Happens to Grass in the Heat?

Hot grass cools itself off using a process called transpiration. Moving moisture out of the leaves. High temperature and low humidity can cause more moisture loss than uptake from the root system can replace. The result is stress and brown wilted blades of grass. 

How badly drought stress damages your lawn depends on the type of grass, how hot for how long, and soil moisture levels. Heat waves are often accompanied by watering restrictions. Your allowance of how much, how often, and how long you can water may be just enough to keep grass alive. Not enough to provide a healthy growing environment.

Some grasses–such as Zoysia–with extensive deep root systems tolerate heat waves easier and recover quickly. Lawn grass with shallow roots has the most heat-related problems. Shallow roots are caused not only by the choice of grass, but by compacted soil, watering habits, the wrong type of fertilizer, and improper mowing.

dry grass leaves dry pasture drought land hot summers europe america no harvest environmental problems due climate change closeup What Temperature Is Too Hot To Mow The Lawn?
Yellow lawn with brown dry grass

When Your Lawn is Too Hot to Mow

A heat wave is a period of unusually hot weather that typically lasts two or more days–according to scijinks.gov/heat. Temperatures have to be above historical averages. Typically soil temperatures will lag behind heat wave air temperatures. Your lawn may not start coming to life for a couple of days after the air temperatures bring relief because of soil heat retention.

Grass should never be mowed when the temperature is above 80 degrees F (26 degrees C). This is true anytime. It is more important during extended hot weather. 

Grass turning yellow or brown is a sign the temperature is too high to mow. Or the soil is too dry. Check moisture by digging down a couple of inches. If it is dry to the touch at that depth, add water. Lots of water in a hot spell. 

Listen to weather forecasts. The more local, the better. Even if you do not have complete confidence, they at least provide some indication of weather patterns. Do not mow if the forecast predicts many days of heat.

Watering a stressed yellow or brown lawn does not mean you can mow it. Resist the urge. Watering will keep the grass alive and ensure it recovers quickly when the heat is gone. 

Mowing the lawn when it is extremely hot can cause significant damage and encourage disease. Dry grass blades can shatter when mowed instead of being cut cleanly. A dull lawnmower blade makes things worse. It can even pull grass out of the ground. Ragged grass is an invitation to disease.

Lawnmowers–especially riding mowers–are heavy machines. They break or damage brown dry grass wherever the wheels are tracking. Just walking on your dried-out lawn causes crushed and broken grass.

Best Time of Day To Mow

If you absolutely must cut the grass when it is hot, cut in the evening after the heat of the day is past. Preferably when the sun is down but before dark. Hopefully, the temperature is down to between 40 and 80 degrees F. Do not mow grass in the morning. Water it instead.

Leave your grass longer–up to 4″. Longer grass helps develop more and longer roots. Longer roots reach moisture that is deeper in the soil. Longer grass also slows down evaporation. Helping to preserve soil moisture. Long grass eliminates competition for moisture by preventing weeds from germinating. 

Make sure the mower blade is sharp. Cut off no more than 1/3 of the grass length. Change patterns every time you mow. Driving in the same place over and over can create ruts and damage grass. Even walking in the same pattern can damage heat-stressed lawns.

How to Help Your Lawn Through a Heat Wave

Lawn care may be even more important when you are not mowing your grass because of the heat. 

  • Watering. Water your lawn longer but not as often. It won’t stay soggy long. The water will soak deeper into the soil, forcing roots to grow deeper reaching for moisture.
  • Fertilizing. Do not fertilize during extreme heat. Nitrogen can burn the grass. Burned damaged grass is more susceptible to disease and weed infestations.
  • Shading. Planting trees around the lawn to provide shade helps cut down the heat, This is a strategy that takes years to be effective but it is a worthwhile endeavor.
  • Mowing. When mowing before or after the heat, cutting your grass too short makes it vulnerable to heat stress. Keep the lawn about 3 inches high after cutting. It shades the soil, slows evaporation, and chokes out weeds.

If It Is Too Hot To Cut Grass, It May Be Too Hot For You

Heat stroke is not a fun experience. Avoid mowing your lawn during the hottest part of the day. Heat exhaustion tends to make people slow and clumsy. A recipe for injury. Know your body and be on the lookout for some of the following.

  • Nausea
  • Dizziness
  • Lightheadedness
  • Fatigue
  • Heavy Sweating. Or no sweating. I have been in heat trouble when I quit sweating; lacking hydration.

Frequently Asked Questions

What are the signs that my lawn is becoming stressed in high temperatures?

Signs that your lawn is becoming stressed in high temperatures include yellowing or browning of the grass blades, slowed growth, and an increase in weeds. Additionally, the soil may become compacted and hard, making it difficult for the grass roots to absorb water and nutrients.

To prevent damage to the lawn, it is important to avoid mowing in high temperatures and to provide adequate water and nutrients to the

What steps can I take to protect my lawn in hot weather?

To protect your lawn in hot weather, make sure it is well-watered and fertilized. Avoid mowing the lawn when temperatures are above 85 degrees Fahrenheit, as this can cause the grass to become stressed and damaged.

Additionally, consider using a mulching mower, which can help to retain moisture in the soil and provide nutrients to the grass.

Can mowing the lawn in high temperatures affect the quality of the cut?

Yes, mowing the lawn in high temperatures can affect the quality of the cut. When the grass blades are dry and brittle, they are more likely to break and become unevenly cut. This can result in an uneven-looking lawn.

Can mowing the lawn in high temperatures lead to wildfires?

Yes, mowing the lawn in high temperatures can increase the risk of wildfires. Lawn mowers can generate sparks that can ignite dry grass or other flammable materials, especially in areas that are prone to wildfires.

Final Thoughts

It’s important to be mindful of the temperature when mowing the lawn to ensure both your safety and the health of your lawn. Mowing the lawn during extreme heat can lead to dehydration and heat exhaustion, as well as cause stress and damage to the grass.

By following the tips and recommendations outlined above, such as mowing during cooler times of the day and keeping the lawn well-watered and fertilized, you can help ensure a healthy, lush lawn all season long.

So go ahead and enjoy your beautiful, well-maintained lawn, while staying cool and safe in the process!