June 24, 2016
Watering Lawns
Some areas have received rain in the past week or two, a few of those areas too much rain, but many areas are quite dry and lawns are starting to show signs of drought stress, especially with above normal temperatures. You don’t have to keep your lawn lush green, but you also want to prevent permanent damage to your turf, especially this early in the season.
Bluegrass lawns can be allowed to go dormant and they will green up when temperatures cool and they receive some moisture. But even if allowed to go dormant, they should receive about a half inch of irrigation weekly if they don’t receive it from precipitation. This will keep the crowns alive and ready to generate new growth when growing conditions improve.
Fescue lawns are a different story. They cannot be allowed to go dormant or turn brown. Once a fescue lawn is brown, it goes into what I call a state of permanent dormancy... in other words it is dead! Again a half inch of irrigation a week should be enough to keep it alive except under extreme conditions.
The biggest problem I see on watering lawns is with people that have automatic watering systems. The first problem is the timing of water applications. It is best to water between 5:00 a.m. and noon. Evaporation losses aren’t as high when irrigation takes place in the morning.
Also, the turf will dry off more quickly once the irrigation stops. The longer the turf blades stays wet, the more likely it is for diseases to develop. This is more likely to occur if lawns are watered in the evening and the grass blades stay wet all night until the following morning.
The other problem with automatic watering systems is they usually put on too little water, often only one to two tenths of an inch of water, with a single cycle. There are two problems with this. First, no matter how much you put on, you’re going to lose some water due to evaporation. With small applications, the efficiency goes down as a higher percent of the water is lost to evaporation.
The bigger problem with light applications is it doesn’t soak into the soil very far. This encourages shallow rooting which creates problems for the turf later in the summer. Your lawn will be much healthier if you put on seven tenths of an inch of water in one application once weekly than if you put on one tenth of an inch of water every day for a week.
You are applying the same amount of water, but a single application encourages deeper rooting, more water will be available to the plants, and you should see a healthier turf. The one precaution to applying more water in a single application is, you should never apply so much water at one time that it runs off rather than soaks into the soil.
Finally, one thing you might not think of, but it affects drought stress on grass is having a sharp mower blade. A dull mower blade will tear grass instead of making a clean cut and those jagged edges on the blade of grass will lose more moisture than will be lost from a clean cut.
If you sharpened your blade at the beginning of the season and haven’t since, it’s probably time to sharpen it again. A good rule of thumb would be to sharpen your mower blades every four to six weeks, but more frequently if you mow a large area.
For more information on caring for your lawn during dry conditions, contact your local Nebraska Extension office.