While seasonal heat is cyclical, an unexpected heat wave poses a different threat, and you'll need to take more action than normal. Your lawn will likely require additional watering during a heat wave, but always water strategically.
Water Early
Cooler temperatures and subtle breezes help to keep evaporation slowed down. Early morning watering is also recommended as watering your lawn during hot parts of the day can add stress to your grass.
Between irrigation and natural rainfall, your grass should receive between 1 and 1.5 inches of water each week during the summer. Water deeply every other day for the best results. Your turf should receive about 1/3 an inch of water every two days in order to maintain deeper roots, thus helping protect against drought.
Although a low-cut, manicured lawn might seem ideal, turf grass actually does better in the summer heat when you let it grow a bit. Longer shoots mean deeper roots, which the lawn needs to suck up whatever moisture is in the soil. A higher lawn also shades the soil, minimizing evaporation.
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. Test whether your sprinkler system is watering your lawn evenly.
Don't water everyday.
Watering everyday makes grass roots shallow. The more shallow your grass roots are, the less hearty it will be in hot weather. Instead water about two times per week for longer periods of time.
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.
Vegetables and fruits that are developing fruit during a heat spell need regular watering to ensure good production. Vegetables typically require daily watering during summer weather, but may need a second watering when temperatures are extremely high.
Watering in the morning also helps your lawn stay cooler throughout the hottest parts of the day, decreasing the amount of heat stress for the turf. If you are unable to water in the mornings, early evening (between 6:00 PM and 8:00 PM) is the next best time.
It is often recommended that you water your lawn early in the morning, as early as 4 am and no later than 10 am. During extreme heat, watering should be done no later than 7 am.
Many grasses can stay in dormancy for 3-4 weeks without beginning to deteriorate to the point of plant death. When the prolonged period without rain ends, the turf is able to regenerate from rhizomes and stolons.
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!
It's Noticeably Wilting
One of the earliest and most obvious signs of dehydration in grass is wilting, when blades begin to curl over instead of standing up straight. If you don't take action right away, you will soon see the grass start to change color (which we discuss in more detail below).
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.
When summer sizzles, a lawn can easily fizzle, trading lush green for crispy brown shades. The causes of brown grass vary. Insect feeding, drought stress, soil compaction, or other factors can combine with heat to damage grass. In this weakened state, a lawn is more susceptible to attack by weeds and insects.
In the blazing summer, when temperatures are between 90-100+, try watering 3-4 times a week.
It is ideal to water lawns about one inch of water per week. To determine how long you need to water to get one inch, place a plastic container in your yard and set a timer. On average, it will take 30 minutes to get a half inch of water. So, 20 minutes, three times per week will give a lawn about an inch of water.
The best time to water your garden in summer is from 6 am to 10 am—before the heat of the day sets in, giving your plants plenty of time to drink up and any moisture on the leaves to dry off before nightfall. What is this? If watering in the morning isn't possible, the next best time is from 4 pm to 7 pm.
Most lawn experts recommend watering your grass until the soil or ground temperature reaches the 40-degree Fahrenheit mark.
It's tempting to water your lawn in hot weather, especially if your grass is already looking a bit thirsty. But in most cases, you shouldn't water your grass when it's 95°F or hotter because the water will likely evaporate before it reaches the roots.