Consider these two options for providing what most of us now commonly describe as “smart” irrigation.

Option Number One: Fetch a pen and paper and a graphing calculator. Next, you need to acquire weather tables for the last couple decades and a comprehensive irrigation textbook. If you can find one, get yourself a chart with ET rates for various plants in your area, and don’t forget the thermometer and a few rain gauges.

Finally, count on spending lots of time calculating the amount of water needed to keep the turfgrass and ornamentals healthy and attractive on each of your clients’ properties.

Option Number Two: Smart controllers.

Which of the two options sounds like the better choice?

Smart controllers (a few of the various models aimed at the residential and light commercial market are profiled below) go far beyond basic time-based (clock) controllers to incorporate factors such as local climate and site conditions, time of year and occasionally soil moisture measurements, to determine an efficient schedule for irrigation, based on how much water the landscape will need.

Having a computer crunch all of these numbers and calculate – on an ongoing basis – irrigation schedules removes what has traditionally been the biggest obstacle to irrigation efficiency: inattention.

“My 30 years of experience in the industry have told me that most time-based controllers get set for the hottest time of the year, and then it doesn’t get touched again until they’re turned off at the end of the year,” says Don Clark, principal product manager for Rain Bird. Surveys, he says, show that these controllers are adjusted, on average, only once or twice a year.

Passing the Test

In the late 1990s, various irrigation manufacturers began to introduce new irrigation controllers for landscape applications that incorporated some of the high-tech features once found only in expensive systems used on golf courses and other large properties.

In 2002, the Irrigation Association organized SWAT (Smart Water Application Technologies), a cooperative effort of installers, manufacturers and water providers charged with creating a protocol to test and identify specific irrigation products and practices that “deliver proven, exceptional water use efficiency.”

The move proved timely, as the smart controller market has expanded dramatically since then. The protocol used has become increasingly more advanced, as well. The program now tests both climate-based and sensor-based controllers, as well as rain sensors themselves. The results of third-party testing on these different products can be found at

In 2006, the U.S. Environmental Protection Agency created the WaterSense labeling program, designed – like Energy Star does for electric appliances – to designate those products meeting a certain standard of efficiency in water use.

In 2012, the WaterSense program added climate-based irrigation controllers to its list of product categories. While the specific results of testing aren’t available with WaterSense, as they are with SWAT, only products achieving “at least 80 percent irrigation adequacy and less than 10 percent excess irrigation for any particular landscape zone with less than 5 percent excess averaged for all irrigation zones” qualify for the WaterSense label. To learn more about the program and see a list of qualifying products, visit

So while watering remains constant, Clark compares plant water needs throughout the year to a bell curve. The middle portion of that bell curve is the summer, when the most water is needed. At each end of the curve (January and December), most regions need little to no water. So other than the peak time for watering mid-year, there’s a lot of overwatering.

“A smart controller is smart in that it takes weather data, usually from onsite, and adjusts the watering time proportionally to match the plant water requirements,” he summarizes of a process that uses ET (evapotranspiration) data to see how much water is being evaporated and transpired through the plant and, thus, how much needs to be replaced to keep the plant healthy.

Most smart controllers use the maximum water needs for a given area during the hottest time of the year, and then adjust that down (or up, in extreme heat) based on the conditions at the time.

Rain Bird’s ESP-SMTe controller takes a somewhat more sophisticated approach and provides what’s called “Managed Allowed Depletion,” explains Clark.

“MAD not only adjusts run time, but also adjusts the frequency, based on root depth and soil type.” This allows for watering a tree, say, every 10 days for a longer duration to get the water down to the roots. But turf, on the other hand, can be watered, say, every other day for a shorter duration.

“Then, if you get an extremely hot stretch of weather, it would water it every day instead of every other day. And all of this is based on scientific formulas and research,” he notes. “It does it automatically.”

Another unique feature with Rain Bird’s ESP-SMTe controller is a tipping rain bucket. While most rain sensors in the class have disks that swell when they get wet and eventually turn the system off, this unit actually measures the rainfall and tips every two-hundreds of an inch.

Clark explains: “So this lets the system know how intense the rainfall was, when it rained, and how much it rained. That’s important, because if a rain event has just occurred and filled the soil to field capacity, any rain that comes after that is useless. Or if it’s rained several inches in one hour, much of that water is just going to run off and be useless to the plant. This system determines how much of a given rain event is actually effective rainfall.”

While this system requires a little more expertise to set up than some other smart controllers on the market, there is greater potential for water savings and improved plant health, claims Clark.

Weathermatic’s SmartLine controller is designed to be simple and affordable enough for the average homeowner to install, but sophisticated enough for irrigation professionals working on high-end jobs, says Martha Golea, marketing communications manager with Weathermatic.

What about watering restrictions?

“Anyone can operate it in basic mode, but its smart mode was developed with the help of experienced irrigation contractors around the United States.”

Golea says that one particularly important feature given irrigation restrictions that have popped up in certain parts of the country is the SmartLine controller’s ability to program around water restrictions. While many controllers must be manually reprogrammed on a regular basis to take watering restrictions into account, the SmartLine allows the operator to be programmed for a specific day of the week then omit the dates that are prohibited.

The settings are good for six months. A cloud-based application makes it possible to enter this information, and also to manage the system remotely in the event of further restrictions.

While water conservation is the key reason to use a smart controller, “overwatering doesn’t just hurt your plants, it leads to cracks in sidewalks, streets, parking lots, foundations and causes puddles where people could slip and fall,” notes Golea.

“Nobody wants to be held financially responsible for those things. So while contractors may be more concerned with the landscape-related benefits of smart controllers, their customers are often quite interested in the hardscape and liability aspect.”

Toro’s new Evolution controller is not, by itself, a smart controller. But the unit is designed so that it can be upgraded to become a smart controller with the addition of optional accessories.

Even alone, the unit does help to improve efficiency by incorporating some smart irrigation practices, says Toro Marketing Manager Burnett Jones.

“You have the capability of doing things like cycle and soak; you have a monthly water budgeting capability; and, even with the standard product, you get the ability to use a free software available from Toro that lets you use a ‘wizard’ to create schedules,” he explains.

By entering the zip code of the site, the software will pull in the maximum ET usage for that location from Toro’s proprietary databases.

“That ET data is based on about 30 years of history,” says Jones. “It takes that value and then, using the Irrigation Association formulas, generates runtimes for that particular situation.”

In addition to creating the runtimes, the Evolution controller will also take into account the different plants being watered on different zones – and the sun exposure/shade, slope and soils – when creating cycle-and-soak parameter, he adds. It also uses historic monthly ET to automatically adjust the schedule monthly, which is a new feature, states Jones.

“That’s a nice feature that, even if you don’t have the optional smart equipment, you can be quasi-smart in how you’re watering,” he notes. “For those who aren’t going to purchase the extra equipment but still want to water responsibly, for no extra cost, this lets them do so.”

The addition of what Toro calls “Smart Connect” accessories turns the Evolution into a true smart controller. A receiver is integrated into the unit, which can communicate with four different types of devices and, in some cases, multiple different devices.

“One option is to use a local, mini weather sensor (the EVO-WS), which uses solar radiation and temperature to measure what’s happening with the weather, and uses that information in conjunction with local ET data, to adjust the schedule, either on a daily basis or on an average of up to seven days,” Jones explains.

Soil sensors (up to three per controller) are also available as smart accessories. “You can assign these to different schedules controlling different areas of the landscape,” he notes, allowing finer control of sun/shade areas or other microclimates. (The weather sensor can also be used in conjunction to control one schedule.)

Onboard software

Hunter Industries takes a comprehensive approach by offering one smart platform, Solar Sync, which can be plugged into any of the company’s controllers, from lower-end residential to higher-end, two-wire, 100-zone systems, says Troy Leezy, marketing manager at Hunter.

“All of the controllers have the intelligence to work with that. They have onboard software built within the controller, and Solar Sync is an external sensor that can be added on to look at solar radiation and temperature,” he explains.

The company also offers a higher-end ET system, which requires operators to enter soil type, sprinkler type, slope, shade and other factors for each zone. “It then drives its own schedule,” Leezy explains.

The complexity involved, and uncertainty when the system is going to run, means this type of system isn’t for everyone. With Solar Sync, the operator programs it for the heat of summer and tells the unit, for example, run for 15 minutes. “Then, Solar Sync looks at solar radiation and temperature and adjusts the controller up or down, depending on what is happening outside,” he explains.

Smart controllers can help to optimize water use, but even the more user-friendly systems do take a little time and thought to set up correctly.

“No matter who the manufacturer of the system is, you don’t just plug it in and walk away,” emphasizes Leezy. “It takes time to balance it out. But, while a basic controller might get adjusted only once or, at best, twice per year, a smart controller is making adjustments every single day. So you’re using the water that the landscape needs; what you’re not using is the water wasted by forgetting to adjust the system down – and that’s the savings.”