HOW OFTEN SHOULD I RUN MY SPRINKLER SYSTEM?
Most local lawn experts say that sunny type grasses need anywhere from 1" to 1.25" of water per week during peek high temperature conditions. On the other hand, it is widely agreed that shade tree grass or cool weather grasses require from 1.25" to 1.5" of water per week during the same peek season. Just as with any other topic, there are widely varying as well as often conflicting opinions concerning the frequency of lawn watering in order to most affectively achieve the necessary weekly precipitation. We will take a look at some of the most popular ideas and discuss their pros and cons.
The first method involves watering 3 to 4 times per week usually 10-15 minutes per spray zone (30-40 minutes for rotary zones) beginning around 3:00-4:00AM. This is the preferred method when the soil profile is of heavy sand or clay. Simply put, water either travels too rapidly through sandy soil or too slowly through clay. It may also be preferable to utilize this method with fescue type grass due to its need to "cool down" after long exposures to high temperatures. The problem with the every-other-day method is that it tends to cause shallow root development due to water not being "pushed" deeply enough into the soil profile. Without a deep root structure the grass is not as drought tolerant and often times more susceptible to infection and disease. It also causes a less healthy thatch which in turn allows more weed seed germination.
Another common method of watering is watering for prolonged periods of time trying to achieve a much deeper moisture penetration. There are not many advantages to this type of watering. Soil is only able to soak in so much water before it naturally superficially saturates, shedding the excess like water off a ducks back either pooling in low lying areas or running off the property altogether and into adjacent properties, or worse, streets.
The method I like to observe is commonly known as "cycle and soak". This is where you run each zone up to its saturation point but not past. This "cycle" time is followed by a "soak" time of approximately 30 minutes, which is followed by another run time. You do this repeatedly until you have achieved the appropriate weekly precipitation. As a general rule, most spray heads will put out approximately 1" of water every 30 minutes, whereas it will take about 2 hours of total run time per rotary zone in order to achieve the same amount of moisture.