True or false? Lawns should be watered deeply and infrequently to encourage deep rooting.

This has been the accepted recommendation for a long time. Again, it sounds so logical to apply enough water to penetrate the soil to 4 to 6 inches so that grass roots grow long enough to take advantage of the moisture.

In the North, we grow cool-season grasses such as Kentucky bluegrass, perennial ryegrass and fescue. They add roots and the plants multiply during the cool of the spring and fall. In the hot, dry summer, grass plants want to go dormant and turn brown. During the hot season, they may actually lose some of the roots they developed during the spring.

Researchers at Michigan State University and other universities have now developed a modified approach to lawn watering that seems to work best. They recommend deep watering, if necessary, during the cool of the spring and fall when roots are being produced. Generally, grass needs about 1 inch of water per week in the form of either rain or irrigation.

During the summer, to keep the plants green and prevent them from going dormant, they recommend a light, frequent watering. This may be 1/10 of an inch per day or 1/4 of an inch every few days. If possible, this routine should be continued throughout the entire period of the hot summer. Some people feel that to start this process and then stop during the steamy days of August may cause considerable stress on the grass.

There also appears to be some benefit to light, frequent watering when it comes to disease control. Certain turf diseases are encouraged by water stress especially during the heat of the summer. As the water transpires (evaporates) off the surface of the grass blades, it provides a cooling effect and helps reduce some diseases.

Watering the lawn also has an impact on how much fertilizer to use. Don't forget that, unless the lawn is being regularly watered throughout the season, the grass plants are not capable of taking advantage of high levels of nitrogen (see article on "fertilizer").

Most recommendations call for a range of 3 to 5 pounds of nitrogen per 1,000 square feet of lawn per year. Generally, non-irrigated lawns only need about 3 pounds of nitrogen per year. This translates into 3 applications timed at about Memorial Day, Labor Day and Halloween.

For a lawn to be able to effectively use 5 applications would require irrigation. This almost always means having an in-ground irrigation system with an automatic control system.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.


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