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How To Keep Your Grass Healthy in a Heat Wave

Updated Oct 14, 2022

Updated Oct 14, 2022

Home > Lawn > How To Keep Your Grass Healthy in a Heat Wave

The United States is currently experiencing a series of record-breaking heat waves. From New England to the Midwest, temperatures have been reaching well over 100°F, with some of the highest recorded in Waco, Texas, at a sweltering 108°F. But, even for non-desert states, temperatures are reaching numbers we haven’t seen before. These heat waves bring many new, difficult challenges for homeowners, including keeping lawns green and thriving.

In this article, we’ll help you keep your grass alive by listing some of the most important tips and techniques for keeping a healthy lawn in the summer heat.

What Kinds of Grasses Are at Risk?

Before adjusting your sprinkler systems and grabbing your hose, you should double-check to see if your grass is at risk. Generally speaking, there are two types of grass, warm-season and cool-season. Warm-season grasses grow during the spring through the fall and are both heat and drought-resistant. These turfgrasses can stand up to hot weather relatively well. However, cool-season grasses grow in the late summer, fall, and early spring and are very susceptible to high temperatures. If you have cool-season grass, you must take extra precautions to keep it alive and hydrated during a very hot summer.

The most heat-resistant and drought-resistant grasses are:

  • Buffalo grass
  • St. Augustine grass
  • Bahia grass
  • Bermuda grass
  • Zoysia grass

Grasses that are the most susceptible to heat are the following:

  • Kentucky bluegrass
  • Perennial ryegrass
  • Fine fescue
  • Bentgrass

How Important is Efficient Irrigation?

lawn sprinkler

The most impactful decision homeowners can make to help their grass survive a heat wave is to practice good irrigation techniques. Correctly watering your grass will ensure that your turf obtains as much moisture as possible by reducing water loss. Effective irrigation is doubly important for homeowners in Midwestern and Southern regions, as many of these states are implementing water restrictions.

Water Deeply

During intense heat and droughts, it’s always best to water deeply and infrequently instead of lightly and more often. Deep, thorough watering ensures less water is lost to evaporation and reinforces deep root growth. Deeper roots create a more stable and drought-resistant grass by allowing its root structure to stretch beyond the top layers of soil that will be dried and fried by high heat. These stronger roots will help weaker cool-season grasses stand up to these abnormally high temperatures.

Typically you will want to add about an inch of water to your yard every day, but during a heat wave, you will want to soak the top 4 to 6 inches of soil about two or three times per week. Most irrigation systems have a soak cycle option, allowing you to set longer soaks and implement deep watering cycles.

As a side note, if you’re trying to keep flower beds hydrated, you should use some mulch, such as bark, wood chips, or pine needles, to add shade and improve moisture retention.

Water Early

One of the most common lawn care mistakes homeowners make is watering at the wrong time. Rumors abound about watering during mid-day to “cool off your plants.” Unfortunately, these rumors are wrong, and watering mid-day can harm more than it helps. Watering your lawn at noon evaporates more water and can fry your grass at extremely high temperatures. Some recommend watering at night or dusk, but this isn’t ideal either, as nighttime watering can lead to the growth of damaging bacteria and fungi. Ultimately, the best time to water is in the early morning. This way, the temperatures are cool and retain the most water, and you won’t have to worry about hazardous lawn diseases that can harm your grass.

Avoid Fertilizer

lawn with brown spots

While it’s generally a great idea to fertilize your lawn, doing so during a heat wave leads to more damage. Fertilizer kick-starts the growth of your lawn, acting as a powerful fuel, making grass grow quicker and consuming more water in the process. The problem is that your lawn is in emergency mode during a heat wave, absorbing and utilizing what little water is available. If you apply fertilizer during a heat wave, the salts from the fertilizer will draw too much moisture from the roots of your grass, desiccating and killing portions of your lawn. Overall, it’s best to avoid fertilizer altogether until temperatures cool off.

Mow More Effectively

mowing a lawn during the summer heat

Good mowing habits can help your lawn survive record-breaking temperatures and improve lawn health year-round. High temperatures and drought create heat stress or signs that your lawn is negatively affected by heat. Incorrect or too frequent mowing can increase this heat stress, resulting in a more damaged yard or, at worst, dead grass. Some common signs of heat stress include withered, brown, or curled grass blades, large dry patches, and brown streaks.

First, you should always try to aim for mowing early in the morning and doing so after it rains. Mowing when temperatures are at their lowest will help reduce the damage the mowing does when combined with high heat – it’s also much safer for you, as mowing during high temperatures increases the risk of heat stroke. Be sure to wait until your lawn is dry after it rains, as mowing when the grass is wet can lead to clumping.

Next, you should raise your mower deck and keep your grass about an inch longer than you normally would. Longer grass promotes deeper root growth and provides more shade for the top layers of roots.

Finally, keep your mower blades sharp. Dull blades lead to shredded and torn grass, which not only increases heat stress but also results in increased moisture loss.

Final Thoughts

Ultimately, keeping your lawn healthy in heat waves comes down to good lawn maintenance practices and a little know-how. However, don’t forget that extreme heat poses an even greater threat to you and your family. Always try to work early in the morning or late in the evening, and if you have to work during the middle of the day, always have a spotter nearby. Heat stroke is a real risk, even for cooler Northern states.

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