If conditions become hot and dry enough, the lawn may even begin to die out in some areas. This will cause the lawn to look thin, weak, or have many dead patches throughout. Fall is a good time to revive your lawn. As temperatures cool and moisture becomes plentiful, some of the brown patches will likely green up.
When your lawn has heat damaged, it doesn't just turn brown — the dead, brown grass will eventually disappear and reveal the ground beneath it. These bare patches of ground are easily susceptible to weeds. This is why you need to cover bare patches of your lawn with seeds in order to try and regrow the grass.
The good news is that the plant can stay dormant for a good while before dying so that, if the water is applied, there can be a full recovery in as little as a few days. These pictures show the damage of heat stress. If your lawn looks like this, water it!
Proper lawn fertilization can also help to remedy an already sunburnt lawn. If you want to get burnt grass green again, make sure that your lawn care company is fertilizing those spots to help provide a boost of nutrients.
If it's due to fertilizer overlap, your lawn probably looks like a checkerboard, with burned (yellow or brown) areas in the middle of each square. Or, you may have very green sections next to brown patches or lines.
Once grass starts turning brown or wilting, or growth is slowing, it's important to hold off on mowing, nutrient, and pesticide application. Most homeowners can tell just by looking at their lawn if it is suffering, whether from heat stress or otherwise.
During a heat wave—a period of abnormally hot weather that lasts longer than 2 days—it's recommended that you do not mow your lawn.
As the heat starts to put stress on your lawn you may notice full brown blades of grass or grass with brown tips. They may have begun to curl.
If conditions become hot and dry enough, the lawn may even begin to die out in some areas. This will cause the lawn to look thin, weak, or have many dead patches throughout. Fall is a good time to revive your lawn. As temperatures cool and moisture becomes plentiful, some of the brown patches will likely green up.
Water deeply and infrequently (2-3 times per week). Morning watering is highly recommended, as afternoon watering can lead to early evaporation, while night watering can cause various forms of turf disease. Refrain from mowing too low.
WATERING SCHEDULE
Deep watering helps to encourage deep root growth. Deeper roots stay cooler and stronger to better protect your lawn and garden from heat stress. Allow a deep watering at least once per week, twice if the temperature exceeds 100 degrees or more for several days in a row.
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.
When the temperature drops below 40 degrees Fahrenheit, the grass will not grow high enough to warrant mowing. A week of consistent temperatures below 40 degrees will close the door on the lawnmower for the season.
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.
Applying too much fertilizer to your lawn will cause the nitrogen and salt levels in the soil to increase rapidly, which can damage or even kill the grass. When this happens, it is known as “fertilizer burn” and looks like yellow and brown strips or patches of dead grass.
Depending on the level of damage done to your grass, you may be able to reverse the effects of fertilizer burn and help your lawn grow back lush and green. The important thing to remember when fixing fertilizer burn is that you need to reduce the amount fertilizer left in the soil.
Water in the early morning – between 6 a.m. and 10 a.m. Midday watering leads to wasteful evaporation, while nighttime watering causes droplets to cling to grass overnight, increasing the chance of lawn diseases.
Highlights. Avoid watering grass on a hot afternoon when it's 95 degrees or higher. The best time to water grass is at dawn or in the early evening. Water deeply three times a week instead of a little water daily.
Watering on a hot summer afternoon is a horrible idea. The liquid will evaporate too quickly and may not reach your grass's roots, so heat and irrigation shouldn't go together. Instead, the best time to water grass during summer is in the morning. The ideal time for morning watering is before 9 AM.
In times of extreme heat, it is vital to water your lawn for about 30 to 45 minutes daily. Once the temperatures drop below ninety, you can cut back to watering three to four times a week, until that blissful thunderstorm comes and quenches your lawn's thirst!
During extremely hot weather (daytime temperatures above 90F and nighttime temperatures above 70F), try to water daily or every other day. In a 10x10-foot garden, this would mean giving your plants 8 to 9 gallons of water each day.
Mowing high gives the lawn a deeper and larger root system, keeps moisture in, defends against weeds and keeps the soil cooler. Mowing too short during dry conditions can injure or wear out dormant grasses to the point where they may not come back during cooler conditions.
There is no way to revive dead grass, but you can keep brown or yellowing grass from dying out. The best way to revive dehydrated grass is to offer moisture as needed.