Installing, operating, and maintaining an irrigation controller can be a do-it-yourself job. Every week I get dozens of phone calls about “how to program my controller”, “my controller is not programmed correctly” or “my sprinklers are on during the day.” Check out the following to get a better understanding of how your controller works and why it’s useful for your landscaping, your wallet, and water saving.
What is a controller?
A controller is a device or electronic “clock” that controls the irrigation system at a given frequency, duration, and start time. It plugs into a 120 volt outlet outside your home or garage. Most systems typically have 12-14 gauge wires running from the controller to each valve. It sends a low voltage (12 to 14 volts) to operate a solenoid, which then activates and opens an electric valve. Water pressure is constantly built up in the valve, so when this signal is received, the solenoid opens and creates pressure in the sprinkler or drip system. As soon as the electric current stops, the solenoid closes, which in turn closes your irrigation valve and stops the flow.
How should this be planned?
Determining how you should program your controller depends on many factors, including soil type, plant type, sun exposure, irrigation system, and external moisture. On sandy soil, a shorter but more frequent schedule is usually required. Clay soil is usually best with one start. For example, on clay soil it may take as little as 6 minutes of running, while the sandy program switches between running for 3 minutes, then waiting for 20 minutes, then running again for 3 minutes. This start-soak cycle allows water to enter the ground without causing flooding, and can be customized by adding multiple start times on your controller.
The best way to know how long to water the soil before flooding is to turn on the sprinkler valve and keep a close eye on it. Once the water begins to collect and drain from your lawn, you will know that you have reached the full capacity it can take in that time frame. For example, let’s say in the 7th minute, water started to drain onto the sidewalk, so now you know that you shouldn’t run this sprinkler valve for more than 7 minutes at a time. Depending on how much water this sprinkler supplies and how much water your lawn needs, you may find that 14 minutes per cycle, three days a week is the right amount. Your plan should be for the controller to start at 10:00 PM for 7 minutes and then again at 8:00 PM for 7 minutes. This will provide a total work time required of 14 minutes, but will allow the soil to absorb the previous water before applying the second. If you operated the valve for 14 minutes in a row, theoretically you would be wasting half of that water because it would pour out into a puddle and flow.
What type of system do I have?
Sprinkler Systems: Sprinkler systems use an overhead application where water is sprayed from a sprinkler head. Some sprinklers release water slowly, like an MP rotator (at 3 gpm), while some extinguish very quickly, like the I20 sprinklers you saw on a baseball field (at 15 gpm). It is very important to know the difference in rainfall and gallons per minute in order to properly set up your system, combined with knowing what type of sprinkler system you have.
Drip systems: Drip systems use half-inch flexible pipes with small emitters to deliver water directly to the plant root system. These types of systems tend to be the most common in recent years because they do not use as much water as sprinklers. The problem with these is that it is difficult to see leaks and know if they are on or not. Droplet emitters can range from 1 gallon per hour to 5 gallons per hour, so it is important to install the correct emitters in the right factories. Once you’ve properly installed the system, you can calculate how much water each plant should receive and program your controller accordingly. Most drip systems run 20-30 minutes per cycle, three times a week.
Bubble System for Trees: Bubble irrigation for trees is similar to a sprinkler / drip hybrid. While drip systems can deliver 1 gallon per hour, many tree bubblers can deliver 1 gallon per minute. This is 60 times the difference in water release, so knowing your system is very important. Most tree bubblers are installed in pipes or directly on the surface, so it is often difficult to observe the system when it is turned on. Most sparging systems should run for 5-7 minutes and only 1-2 times a week. Trees do not often like deep watering, while lawns prefer shallow watering more often.
Feel free to dig a little through your irrigation system and find the perfect setting for your controller. It is very important to understand what kind of application system you have and what type of delivery system you are using. At the end of the day, listen to your landscaping, it will indicate you over- or underfilling. In general, most terrain is waterlogged, so before adding time to the controller, be sure to dig in around your struggling plants to check the moisture content. If it is humid, you are probably watering too much water.
As we get closer to Phase 1 of Santa Cruz County Drought Limitations, reducing your greening water use by up to 30% will greatly help you in your overall savings!
Justin White is the CEO of K&D Landscaping, headquartered in Watsonville, California, which won the 2020 Business of the Year by the Pajaro Valley Chamber of Commerce. White is also the current president of the California Landscaping Contractors Association (CLCA) Central Coast local chapter. He is affiliated with several non-profit organizations throughout the community. For more information on landscaping, outdoor and gardening, contact K&D Landscaping at kndlandscaping.com.