For Release June 25, 2002

Lawn Watering Protocol

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

With summer officially underway, there are now a lot of homeowners trying to keep their lawns as deep green as possible through all of the Kansas summer extremes. The problems that the homeowner will encounter in this quest are numerous, but not insurmountable!

Most lawns, in our area, are cool season grasses either tall fescue or bluegrass. The natural inclination of these grasses is to go dormant in the summertime when it is hot and dry. So trying to keep them green during most Kansas summers is making them go against their natural tendencies. It can be done, it just becomes a challenge.

The other option is to let the lawns go dormant. If you choose this route, you still need to see that the lawns receive a little bit of water every few weeks. If a dormant plant gets too hot and dry, the crown can dry out and die. One good deep soaking every three to four weeks is usually enough to keep the plants from dying. One word of caution, avoid vehicular traffic on dormant grass as permanent damage to the crowns can occur.

If youíll look at the cool season grasses, and I mean get down on their level and look at them closely, youíll see that their leaves grow vertically. To maintain a healthy plant with a deep root system you need to leave as much leaf area as possible to produce food and shade. That requires you to mow the grass as tall as possible. For bluegrass, mow 2.5 to 3 inches tall, for improved fescue, 3 to 3.5 inches and for good old K-31 tall fescue, at least 3.5 inches.

If the grass is growing slowly, donít feel like you have to set the mower lower and cut it anyway. Just leave it alone and wait until it has enough growth to justify mowing. Constantly mowing the grass shorter and shorter leaves less leaf area to produce food. It also provides less shade to keep the ground cooler and exposes more bare soil, giving weeds a chance to get a foot hold with the next rain. All the lawn irrigation in the world can go for naught if you are mowing too short. A guaranteed way to develop a crabgrass problem is to mow short and water often and lightly!

How you water your lawn is equally important to the other management factors. Prolonged periods of wet grass plants WILL create disease problems. Once started, these disease problems will plague you the rest of the summer. They may not kill the lawn, but you wonít be happy with the way it looks. Therefore, lawn watering should be done during the morning only. Anytime between 3 and 10 a.m. is ideal. The lawn is often wet then anyway from dew and temperatures and wind speeds are usually lower then as well, so you have better water distribution and less evaporation waste.

The worst time to water a lawn is from mid-afternoon through evening. Any cooling effect from the water is soon lost, you lose more water to evaporation and are more likely to encounter sprinkler pattern deformation from the wind. Which means youíll have spots that donít receive as much water as they should. Watering during this time also increases the likelihood of disease problems developing.

You should also avoid daily light irrigation. You are better off to water every 4 or 5 days and then water more deeply. Grass roots will only develop where there is moisture in the soil. If the only moisture is in the top inch of soil, you wonít have a well rooted lawn now, will you?

It is not impossible to keep a cool season lawn green during the summer. It also isnít necessary to keep it deep green to keep it alive. But if you decide to try, make sure you irrigate and manage your yard properly so you donít create even more problems!

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