Smart Irrigation Scheduling

Proper irrigation scheduling includes understanding soils, plants, and irrigation systems. Adjusting sprinkler runtimes requires knowing how fast sprinklers apply water, how much our landscapes need, and which methods best save water and keep landscapes healthy.

Image of a brown shingle wall with a grey irrigation controller and hand holding up a smartphone with and irrigation app displayed on the phone.

Efficient irrigation scheduling is important for saving water and keeping landscapes healthy. Understanding your landscape and your irrigation system helps you make sure your plants get just the right amount of water. By setting your irrigation controller correctly, you can make sure your plants get the right amount of water throughout the season. Adjusting runtimes with the “Seasonal Adjust” feature, understanding how fast different sprinklers apply water, and using “cycle and soak” methods can help you use water wisely. These practices not only save water but also help your landscape grow strong and healthy.

Precipitation Rate

Several factors determine how long you need to run your sprinklers, including sprinkler type, plant type, and time of year. The precipitation rate of sprinklers is simply how quickly your system applies water, measured in inches per hour.

Types of sprinklers include rotor, spray, high efficiency, and drip:

  • Rotor sprinklers apply water slowly, with a precipitation rate of .3-.5 inches per hour (less than a half inch!).
  • Spray sprinklers apply water quickly, with a precipitation rate of less than 1 inch to more than 2.5 inches per hour.
  • High-efficiency sprinklers apply water slowly and efficiently, with a precipitation rate of .4-1 inches per hour.
  • Drip irrigation is the most efficient and slowest, with a precipitation rate that depends on the emitter style.

Collage of 4 sprinkler types: spray, rotor, high-efficiency, and dripline.

You can calculate your precipitation rate at home using a free rain gauge from the City of Bend Water Services Department: call us at 541-317-3000, ext. 2 or send us an email at: conservation@bendoregon.gov

Water Needs for Different Landscapes

Lawns in Central Oregon need about 1.5 inches of water per week during peak season. Shrub areas need about half that amount. Native plants will only need occasional watering once they are established.

WaterWise Landscape Balance

The following describes the water need for approximately 1,000 square feet of landscaping:

  • High Desert native: 1,869 gallons per year; very low water need.
  • Mixed native / non-native: 5,607 gallons per year; low water need.
  • Lawn and landscape: 11,214 gallons per year; moderate water need.
  • Lawn only: 14,954 gallons per year; high water need.

Adjusting Runtimes

Use the “Seasonal Adjust %” feature on your controller to change the runtimes for all your stations with one adjustment. This is an easy way to ensure your plants get the right amount of water as their needs change throughout the season.

In spring, set the runtimes for each station based on what your landscape needs in July. Then, adjust the Seasonal Adjust % once a month to make sure your landscape gets just enough water. This can help save water and money while keeping your landscape healthy. As irrigation technology progresses, these water saving adjustments can now be done automatically, and can even be changed remotely from your smartphone. WaterSense labeled Smart irrigation controllers can utilize weather data and remote capability to automatically make adjustments to your runtimes based on the current weather. Data shows that these controllers can result in an average 26% water savings when used appropriately. (Rebates are now available for these controllers from the City of Bend.)

Smart irrigation controller, gray in color, mounted to a tan wall.

“Cycle and Soak”

Many irrigation sprinklers apply water faster than your landscape can absorb it. Using “cycle and soak” techniques means splitting runtimes in half and adding a second start time to “cycle” irrigation into smaller, more manageable amounts. This helps more water reach plant roots through the soil and reduces runoff.

Instead of running each lawn sprinkler zone for 10-15 minutes, run each zone only for the amount of time the soil can absorb the water (so it doesn’t run onto the sidewalk or street).

Here are how many minutes it takes before irrigation runs off Central Oregon soils:

  • Fixed Spray (2.5 inches per hour): coarse sand – 8 minutes; sand – 7 minutes; sandy loam – 6 minutes.
  • Fixed Spray (1.5 inches per hour): coarse sand – 10 minutes; sand – 8 minutes; sandy loam – 7 minutes.
  • High Efficiency (1 inch per hour): coarse sand – 22 minutes; sand – 15 minutes; sandy loam – 10 minutes.
  • Rotors (.4 inches per hour): coarse sand – 70 minutes; sand – 60 minutes; sandy loam – 50 minutes.

Example Runtimes

For an average irrigation system during the peak season month of July in Bend, you can calculate the total minutes per week needed. This total is then divided by the number of irrigation days per week on an even/odd day schedule. The cycle and soak method splits this daily runtime in half and adds a second start time to maximize water infiltration and reduce runoff.

You can calculate runtimes if you know your system’s precipitation rate by dividing the weekly water needed by the precipitation rate and multiplying by 60. For example, (1.5/2.5) * 60 = 45 minutes per week.

Smart Irrigation Controllers

Too busy to monitor and adjust your system, smart irrigation controllers are another option. Smart irrigation controllers adjust watering times based on weather conditions, unlike traditional controllers that follow a preset schedule regardless of the landscape’s needs. This technology helps reduce water wastage by about 30%. Although smart controllers are more expensive and require a complex setup, the savings start immediately after installation. It’s advisable to hire a certified professional for installation, but keep in mind that smart controllers won’t fix issues like leaks or poor design in your irrigation system.

Smart controllers manage watering using either signal-based or sensor-based methods. Signal-based models adjust schedules based on weather data received via radio, cellular, or internet, often with a small annual fee. Sensor-based models rely on local measurements of moisture, temperature, and humidity, avoiding signal fees but possibly requiring maintenance. If you frequently adjust your current controller, a smart one may not be necessary—but if you don’t, it could help conserve water. For more information on different models, visit local irrigation supply stores in Bend or contact conservation@bendoregon.gov with any questions.

Leaks at the Sprinkler

Smart irrigation controllers are great at creating irrigation schedules but not great at repairing broken systems! You’ll need to maintain your system. Sprinkler heads can get damaged easily by maintenance equipment, freezing or accidental impacts. If water is escaping from the top of the sprinkler when it’s running, it might be due to a cracked sprinkler body or a faulty wiper seal, which should be replaced. Even though these leaks seem small, they can lead to a lot of water being used, especially during peak season.

Collage of images of various broken sprinklers.

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