Though children may not be impressed with the logic, watering your lawn in the middle of the day, when it's windier and temperatures are higher, results in more evaporation.
Tips for keeping your lawn healthy
From eNews, July 20, 2006
It doesn't take a scientist to tell you your lawn has been suffering through the hot, dry weather prevalent in Minnesota during the past nine weeks.
But it might take one to tell you what lawn care advice to follow.
A labyrinth of information exists on the Internet, including recipes for remedies and tonics that allegedly help grass during dry spells: Water your lawn sparingly. Don't water your lawn at all. Pour a concoction that includes beer, pop, and mouthwash on your lawn.
When rainfall doesn't seem to be forthcoming, one of the best ways to rescue your lawn is through timely, appropriate watering, says Bob Mugaas, a horticulturist with the University of Minnesota Extension Service.
For a green, actively growing lawn, Mugaas recommends applying about 1 to 1.5 inches of water on your lawn every 7 to 10 days. Where some loss of green color can be tolerated, he suggests applying at least one-half to three-quarters of an inch of water every 7 to 10 days.
He adds that as a general guideline, during hot and windy conditions, intervals between waterings should be shorter due to an increased rate of drying.
"Lawn grasses will let you know when they are getting thirsty," Mugaas says. "When you start seeing areas of a dark, bluish-gray color in your lawn, that's a good indicator that the lawn is beginning to dry out, and some additional water will help ease that stress."
According to Mugaas, Minnesota grass plants have relatively good tolerance to hot and dry periods, especially where they have been conditioned properly. But there are limits to that tolerance, especially with many of the contemporary bluegrass and perennial ryegrass varieties that have been introduced over the last several decades.
If the plant gets too hot and/or dry internally, tissue damage can occur and the plant usually dies, according to Mugaas. That's why it's not a good idea to let lawns go dormant or completely dry and brown for extended periods of time.
Owners of automated lawn watering systems can increase the amount of time water is applied and increase the time periods between waterings, Mugaas says. This can help accommodate community water restrictions such as odd-even or address-based watering schedules.
He also recommends applying water early in the day. Normally, winds aren't high and temperatures are cooler, allowing for maximum absorption. Watering in the middle of the day, when it's windier and temperatures are higher, results in more evaporation.
Lastly, Mugaas says to minimize traffic on lawns during extremely dry conditions. Avoiding hard play and heavy traffic will help prevent your grass from permanent injury.
--Source: Bob Mugaas, Extension Service horticulturist