Watering
The importance of watering your lawn properly can never be stressed enough. Your lawn is between 75% and 85% water by weight, and water helps nutrients and other organic compounds to move throughout the grass plants. Water also protects grass plants from sudden temperature changes through its capacity for cooling, and it helps to keep grass cells turgid (or rigid) - which makes your lawn more wear-tolerant.
In hot summer weather, regular watering is more important than
ever. The basic rule of thumb is to ensure that your lawn gets from 1"
to 1 ½" of water per week from rainfall or sprinkling, and the soil
should be soaked to a depth of 6" with each watering. The best time to
water is early morning, since evaporation rates are lower in cooler
temperatures.
Remember that your trees and shrubs will benefit from regular watering as well. In the absence of rainfall, your trees and shrubs will benefit from a long, deep soaking once per week.