Iowa summers are hot. Okay, really, really hot - and those hot temps can be tough on lawns. Lawn grass in Iowa typically likes to be between 65 and 80 degrees. Warmer than that (which it often is), and lawns will go dormant. Though prolonged drought can stress grass, dormancy is not necessarily a bad thing. In fact, it could be what keeps your grass alive until it cools down.
Watering your grass
Adam Thoms is a professor specializing in commercial turfgrass management at Iowa State University. Thoms says either allow your lawn to go dormant, or water frequently. He says the worst thing you can do is attempt to support your lawn by watering, but doing it infrequently. By watering infrequently, (say randomly once every two weeks) you're bringing the turf in and out of dormancy, which uses up the food and energy supply of the grass.
Lawns can go dormant for up to two months at a time and still come back healthy. So don't water every time you think your lawn is thirsty - either water frequently, or let it be. And also remember - letting it be is good for the water supply as well. When it gets really hot and dry you may be asked to cut back on watering your lawn, which can contribute to dormancy stressing as well.
If you decide that you want to keep your lawn awake during the hot months, the best time to water is in the morning, not at night, according to Thoms.
Other hot lawn advice
Thoms says spraying weeds in temps above 90 degrees is a futile effort, because weeds will shut down and go dormant just like grass.
Thoms says it's also futile to aerate your yard in hot temps. Wait for cooler temps and when your lawn comes out of dormancy to begin aeration and seeding. In Iowa, this usually takes place between mid-August and mid-September. If you have alternative lawns with native plants, the best time is early October.
Aeration is also more effective when there's some moisture in the ground. Keep in mind that the main benefit of aeration is to allow oxygen to penetrate into the root zone. It also helps the ground absorb water better by creating less impacted space.
As far as fertilizer goes, wait until mid-September, and remember to use slow-release rather than quick-release fertilizer. It's better for the environment.
