Why Water ?
Natural rainfall typically won't provide an adequate or evenly distributed amount of water. A lawn is better off with a good watering that will soak the lawn to the proper depth one to two times a week. The best rule of thumb is infrequently but deeply. Watering small amounts frequently can cause more annual weeds, shallow root system and a greater chance of disease activity. Too much watering can replace the oxygen in the soil and cause the grass to yellow and sometimes die.
How Much Water ?
As a rule of thumb your lawn will need 1 to 1.5 inches of water a week. This will wet the soil 4-6 inches deep. Keep in mind more water may be required under trees where ther is more competition for moisture. Southern facing slopes will also require more water due to the extra exposure to the sun. When the temperatures exceed 85 degrees it will require an additional half inch of water weekly. If you have heavy clay soils or you are watering on slopes it will be helpful to do shorter watering cycles and allow the water to soak in. Then repeat your cycles until the proper amount has been achieved. When you feel you have watered enough, stick a screwdriver in the ground to see if you have gotten the soil moist 4 to 6 inches deep.
When to Water
The best time to water your lawn is in the morning when there is generally less wind and heat. Watering during the heat of the day is ok but will require more water due to evaporation. Avoid watering in the evening. This will allow the grass to stay wet all night creating a perfect environment for disease activity. Look for signs that your lawn needs moisture such as leaving footprints when you walk over it. You will also notice a blue green tint to the grass when water is needed.
What if I can't Water ?
Sometimes with our busy schedules and possible watering bans during the heat of the summer it can be difficult to water the proper amounts. During these times it is important to keep the crown and roots alive. This can be achieved by watering one half to an inch of water every 2 to 3 weeks. Keep in mind the grass on the top will harden off and become dormant as a defense mechanism to survive. You will typically see some grass thinning and aeration and seeding will be needed to thicken things back up in the fall.