One time when it is a great idea to water during the day is during extreme heat waves.  Grass plants in our area do not like temperatures over ninety degrees.  High temperatures cause great stress to the grass plant causing quality of color and health to decrease.  Whenever temperatures consistently reach the nineties you should suggest to a customer that they run their irrigation system for about ten minutes per zone in the heat of the day.  This is normally between noontime and two p.m.  By watering at this time of day the customer will not be getting any water into the root zone of the lawn but will be lowering the air temperature directly above the grass drastically.  This practice is often called “syringing.”  

For customers who do not have irrigation systems watering becomes much more of an issue.  In many cases these customers are much more understanding of the entire process because it is much less of an exact science.  Very simply put, a lawn should be watered when it needs water.  Because we have complicated watering so much in our pursuit of thick green lawns I think that this concept has been lost.  The lawn should be watered when it needs water.  It really sounds funny and simple but it can be a major issue in our pursuit of proper cultural practices.