This is the time of the year that separates the “men from the boys” with regard to lawn care. In my travels around area neighborhoods, it is interesting to see the variations in lawn quality. The most glaring problem is scalping. Scalping occurs on the lawn of the person who never adjusts the height of the mower.
Usually this is done out of laziness: “If I mow it REAL short, I won’t have to mow again so soon.” While this statement is true, it doesn’t address the issue of what the lawn looks like for the next week or the problems inherent in a scalped lawn during hot weather. When the lawn is mowed too short, the sun beating down on the soil will heat up the soil to levels unacceptable for healthy grass. Give the lawn (and yourself) a break and let it grown to 3″ or more until mid-August or so. The extra blade length will allow the lawn to shade itself, keeping the soil temperature at a level that the grass can withstand. The blades of the grass can tolerate the heat whereas the roots are severely damaged or killed by extreme heat. Once temperatures moderate, you may lower the blade and mow the lawn at about 2″.
There’s always a lot of discussion this time of year about how much and when to water the lawn. As usual, I have an opinion about this, too. Properly mowed (tall), the average lawn will need to be watered very little. If you water lightly and frequently, the grass gets dependent on this surface water and never has an incentive to send roots deep into the soil. The shallow root system that develops will eventually lead to a thatch build-up. If you feel the need to water, run your sprinkler long enough to soak the soil at least 6″ deep. This usually takes 4-6 hours per area, depending on soil type. The best time to water is during the pre-dawn hours. Evening watering leaves the grass wet all night, promoting diseases.