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.
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.
Typically, most lawn irrigation periods during the summer should last between 25–30 minutes each. This amount of time depends on a lot of different factors though. As previously stated, each irrigation system or sprinkler can deliver different amounts of water and it's important to hit that 1 inch per week requirement.
Water at the right times
If you water during hot periods of the day, most of the water will evaporate, and won't absorb into the lawn. "Avoid the urge to water if it's humid," advises Craig Elworthy, founder of Lawnbright "You may think giving your lawn some water will help - but your lawn is actually fine.
Don't water everyday.
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. The local lawn companies I have spoke with around my area (North Central Texas) recommend about 20-30 minutes per watering cycle twice a week.
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.
If it's 70-80 degrees outside try watering 2-3 times a week. During the spring your lawn will be fairly easy to manage so you don't have to water all the time. In the blazing summer, when temperatures are between 90-100+, try watering 3-4 times a week.
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.
During really hot weather, water your vegetables at least two to three times a week. Watering the garden deeply is critical. The water must go down, down, down to encourage deep roots and get away from the hot soil surface.
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.
1) Watering for Too Long
This should be no more than three times per week. Set a timer for 20 minutes and stick to your schedule, even if you think the lawn needs more water. You don't want to oversoak it.
Most grass needs watering between 20 to 40 minutes at a time. Water your grass one to three times a week in peak growing seasons. Your grass type, region, and amount of rainfall impact watering times. Watch out for signs of too much or too little watering to avoid disease or dead grass.
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 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.
Grass needs the benefit of the day to dry and heal before dusk settles. Since mowing your grass in the early morning can damage it and mowing it during the early afternoon can burn it because of all the high temperatures, the ideal time is mid-morning. That is of course if you're free during that time of day.
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.
If you forget or are too busy to water your plants on some summer mornings, you can water them at night. However, this should not be your ordinary watering time. Morning is the proper time for watering plants, though you should keep in mind that not all plants need daily watering.
So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule.
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.
Grass can turn brown and go dormant when it's stressed by drought, heat, or both. It's your lawn's way of conserving energy and water, Mann explains. The grass will break dormancy and begin growing again when the temperatures and/or rainfall levels become more ideal for it.
There's no cut-and-dry definition of a deep watering. Most gardeners generally refer to it as when water has soaked at least eight inches into the soil. This gives plants the structure required to survive lack of water, whether from a drought, a busy gardener, or other environmental stresses.
If the outside temperature is between 90 and 105 F, it can cause heat cramps. If between 105 and 130 F, heat exhaustion can occur. If above 130 F, it can cause heat stroke. When things reach this point, there can be loss of consciousness, skin can turn red, there can be nausea, vomiting, dizziness, and other symptoms.