Summer months bring warm temperatures and sometimes periods of dry weather to the lawns of Northern Illinois. Grass lawns across Antioch-Gurnee-Waukegan and Lake Forest enter survival mode to withstand the stress associated with this time of year. There are several cultural practises that can help maintain a healthy green lawn through these periods of stress. Proper mowing height and watering practises are two of the most important things to do properly as summer begins.
With the forecast of multiple 90 degree days ahead and no rain in the forecast, begin watering now to prevent or assist with heat stress on the lawn. A bluegrass-based lawn needs about 1 inch of irrigation per week to keep adequate moisture levels and to prevent the onset of browning and dormancy. Although this amount of irrigation is adequate for moisture needs it doesn't always keep a lawn from going dormant, but it does give it the best chance to stay green during heat stress.
When soil temperatures get above 90 degrees bluegrass can begin survival mode which consists of opening stomata (cells that release moisture in an effort to cool the plant) making the lawn look thinner as the leaf tissue dries out. Next it will begin to draw moisture back into the crown of the turf leaving the grass blades to turn brown. This doesn't mean the grass is dead, just beginning to show signs of dormancy which helps it survive summer stress. A well planned watering program will help keep the lawn healthy and green as the stress begins. Watering before or at the beginning of a dry spell can delay the effects of heat and lack of moisture. When the forecast doesn't call for rain for more than 5 days, begin a deep and infrequent watering schedule for the dry spell. With summer temps in the upper 80's, windy days and longer periods of direct sun rays the evapotranspiration rates of the lawn escalate quickly, which can leave your lawn with inadequate moisture for ideal plant health in just a few days.
Along with watering regularly during hot and dry summer months the lawn should also be mowed properly. Less frequent and at a taller height will keep activity on the grass to a minimum and allow for full shading of the soil below with longer leaf tissue. Also be sure that when you do mow the lawn, never remove more than a third of the leaf tissue height or else additional stress and moisture removal will be unnecessarily added to the lawn that is already stressed out.