If you want to keep your lawn green through a heat wave, here's how to do it, with directions from Ward Upham of K-State:
* Make sure water reaches about 8 inches deep. Push a wooden dowel or a metal rod (rebar or electric fence post) into the ground to see how far it goes before hitting dry soil.
* Place a tuna can or something similar in the lawn to see how much water is applied in how long a time. Water for 15 minutes and check the depth of watering. If the soil is moist only 4 inches deep, water another 15 minutes. Check again to be sure moisture reaches the desired depth. If you see any run-off before the soil is wet to the desired depth, you may have to run two cycles back-to-back to allow time for the water to soak in from the first cycle before adding additional water. If there is still runoff before water reaches the desired depth, more waterings per week may be needed to make up for the shallow depth the water is reaching. On such lawns, core aeration during September would be highly recommended to help increase the rate at which the soil absorbs water.
* During most of the growing season, watering once a week is adequate. But during extreme heat or on heavy soils where runoff occurs quickly, twice a week may be needed. _ Annie Calovich