There are many factors that determine how well an irrigation system will perform. The core elements considered during the design phase and sprinkler selection have a profound impact on the system’s performance. However, irrigation scheduling is often overlooked. Even the best designed systems can be ineffective if the system is run too often or not enough.

The first thing to determine is how much water needs to be applied to turf grass per week. After you determine how much water your turf grass requires in a given week, then work backwards to find out how long each zone of sprinklers should run. There are many other factors that influence your water requirement. The amount of use your fields are receiving per week, mowing schedule, soil type, root depth, and site micro-climate conditions are key elements to consider when making this decision.

Secondly, determine your start time. There can be many variables that can affect your start time, but three of the most important are temperature, wind and time of day. As the temperature rises during the morning hours so does the wind speed. Temperature can also affect your nozzle performance as the day heats up. This is one of the reasons why early morning is the best time to irrigate. Your turf grass is also more susceptible to disease by watering late in the evening or at night. By watering infrequently at longer durations you will have much healthier turf.

The third element to effective irrigation scheduling is to abolish the “set it and forget it” mentality. This is a common mistake that is made from golf courses, sports field facilities down to the average residence. When the seasons change your watering time should change as well. This is one of the things that can be overlooked the most when maintaining an irrigation system. In July at the peak of irrigation season, your turf typically needs everything it can get. But the shoulder months of May / June or late August and September is when irrigation schedules should be scaled back, but often are not.

Cooler temperatures and more rainfall at this time means we can dial back our schedules – often more than 50%. If you don’t, it is a missed opportunity and you are effectively sending water and money down the drain. Evapotranspiration (ET) management includes effective measurement of rainfall and calculation of actual water lost based on weather readings. This tool used to be only in the realm of large central control systems. Today even stand-alone clocks have it. ET management can automatically stop irrigation when it isn’t necessary; but don’t confuse this with rain sensing. A sensor can’t tell if you had one tenth an inch of rain or ten inches of rain. ET management considers all the elements that govern plant water use and loss: temperature, solar radiation, humidity, and wind. Measuring rainfall is the final step to make sure you don’t add more or less water than is necessary. If you’re not measuring rainfall… you’re still wasting water.