Gardening With Allen: Deep root system is crucial in heat

My lawn is developing brown patches and my flowers are going out of bloom in this heat wave we have been having. I am watering more often but it does not seem to help. I need help.

More frequent irrigation is necessary for plants in containers because they have a limited amount of soil for the roots. However, with lawns, flowers and other plants growing in the ground, a better approach is longer irrigation times. The idea is to develop a deeper root system that is more tolerant of the heat.

It is easy to check to find out if brown patches are receiving less water. Place shallow cans such as a tuna fish cans on the brown area and the green area. Turn your sprinklers on for a specific amount of time and then measure how deep the water is in each can. You will probably find that the brown area is receiving less than half as much water. You may find that one or more sprinkler heads are out of alignment and just need to be turned slightly. Or a sprinkler head has become plugged with a small rock that needs to be removed.

July and August are the highest water use times of the year. We have a combination of warmer days, hotter temperatures and less rainfall. All this adds up to a higher evapotranspiration rate. Evapotranspiration is a combination of evaporation of moisture from the soil and transpiration from plant leaves. Leaves emit water vapor from their leaf pores for cooling.

The best way to irrigate your lawn and other landscape areas is to apply enough water to reach the full depth of the root system. You can develop a deep root system by allowing the soil to dry between irrigations. It requires at least 1/2 inch of moisture to reach 6 inches deep. A 10 minute irrigation will only wet the top inch or so of soil. It is better to water for 20 or 30 minutes and then wait two or three days between irrigations.

You can determine how long it takes to deliver ½ inch of water by using those same shallow cans. Measure how much water accumulates after a specific time such as 10 minutes. Then calculate how long it will take to deliver a half inch.

Another benefit of letting the soil dry between irrigations is that you have fewer weeds. Weed seeds are stimulated to grow when the soil is constantly moist.

Some flowers are more tolerant of high temperatures than others. Most will come back into bloom when the temperature returns to normal.

You may be able to stimulate blooming by fertilizing or pruning to stimulate new growth.