Most lawn experts recommend watering your grass until the soil or ground temperature reaches the 40-degree Fahrenheit mark. It is true, less water is required and needed when the temperature drops.
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.
Fall means cooler temperatures, which is great for lawns. However, you'll still want to water your grass until freezing temperatures arrive. When it's freezing outside, water won't penetrate the frozen ground, so avoid watering when the temperature is 30 degrees Fahrenheit or below.
During extremely hot weather (daytime temperatures above 90F and nighttime temperatures above 70F), try to water daily or every other day.
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.
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.
Experts advise the best time to water your lawn is early morning or late evening when it's cooler. If you water during hot periods of the day, most of the water will evaporate, and won't absorb into the lawn.
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.
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.
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.
Watering after fertilizing washes the fertilizer off of the grass blades and into the soil, where it can get to work nourishing your lawn. It's also important because if fertilizer sits too long without being watered in, it can burn the grass.
Fall. The end of the growing season usually won't require as much watering, since temperatures start cooling and precipitation often increases. Also, most hardy plants will start slowing down their growth and losing leaves in preparation for winter, so they need less hydrating.
Thoroughly Water plants if it's not going to rain before the freezing temperatures arrive. It may sound illogical. However, a moist ground stays warmer than dry soil. Watering the night before the freeze comes will insulate the root structure of the grass and plants and decreases the potential for cold injury.
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.
Water plants deeply, ideally first thing in the morning while temperatures are still low and transpiration rates are low. Potted plants will probably want to be watered more than once a day during a heat wave. The next best time to water during hot weather is in the early evening.
When working in the heat, drink 1 cup (8 ounces) of water every 15–20 minutes. This translates to ¾–1 quart (24–32 ounces) per hour. Drinking at shorter intervals is more effective than drinking large amounts infrequently. Do not drink more than 48 oz (1½ quarts) per hour!
This may seem like a no brainer, but watering grass during extreme heat is the single most important thing you can do to keep it alive. We recommend watering daily with heat like this, but please be sure to abide by local regulations for water usage in your state. It also matters what time of day you water your lawn.
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.
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.
When water starts to boil at 100∘C, the temperature does not rise in the thermometer. All the heat energy is used by the water particles to overcome the interparticle forces of attraction and to change their state from liquid to gaseous.
Superheated water is liquid water under pressure at temperatures between the usual boiling point, 100 °C (212 °F) and the critical temperature, 374 °C (705 °F).
As water boils at this temperature, it changes from a liquid to a gas. That gas, or water vapor can continue to rise in temperature. Liquid water however becomes unstable at 212 degrees Fahrenheit or 100 Celsius and cannot “boil” in as it will have already transformed into water vapor.
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.
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.