Programming Irrigation Controllers

According to Kevin Gordon, senior product development manager, Hunter Industries, San Marcos, Calif., after years of gaining experience working with irrigation controllers, landscape contractors develop a ‘rule of thumb’ as to how much water should be put down daily or weekly in their local service areas.

The problem with this theory, Gordon explained, is that contractors follow their ‘rule of thumb’ and then leave the rest up to the homeowner to figure out.

"A ‘rule of thumb’ as far as water compensation goes in a landscape cannot and will not work for every landscape in a certain area," Gordon said. "Each landscape is different and contractors should be looking at the water needs of every job individually."

Elements such as soil type, moisture loss, angle of slope, amount of sunlight, degree of shade and wind and type of plant material are all factors that can change slightly or dramatically from landscape to landscape. To program an irrigation controller efficiently for each landscape, contractors need to consider and address each of these factors.

THE CONTROLLER. There are two classifications of controllers contractors have to choose from when trying to fit the right controller to each of their customers: electromechanical and digital.

"Digital gives you more flexibility and more programs while electromechanical offers simplicity with a single program," Gordon explained.

Ninety percent of the industry uses digital controllers, according to Gordon, but he doesn’t expect electromechanical controllers to completely disappear from the market.

"There are times when electromechanical controllers are the better choice," Gordon said. "If you have a customer who won’t use an ATM machine to withdraw cash, then they probably won’t be comfortable with a digital controller. The type of controller contractors choose to install in each of their landscapes will be contingent on their customers’ specific needs. Every other aspect of programming the controller is dependent on the selection of the controller itself."

The placement of the controller is also important. They should be placed where they are easy to reach, such as obstruction-free on a garage wall at eye level, Gordon suggested.

Contractors should ask themselves two questions before deciding where to place the controller, Gordon said: ‘Where are the valve wires coming from?’ and ‘Where is the power source coming from?’

"You want to mount a controller close to the electricity so a bunch of large extension cords aren’t needed just to connect it and you don’t want to mount a controller to a wall if you can’t get the valve wires through that wall," he said. "Also, the controller should always be placed at eye level – most contractors place them too low, " Gordon added.

THE ELEMENTS. If a professional, experienced contractor is installing a landscape and irrigation system, then typically plants will be grouped together according to water needs as well as other environmental needs, which is the proper way to install a landscape. When an irrigation contractor installs a system on an existing landscape, hopefully, the contractor who installed the plant material kept this in mind.

"The sharp irrigation and nursery contractors typically try to put similar plant material on the same irrigation zone," remarked Chip Kah, president, K-Rain, Riviera Beach, Fla.

"If a landscape isn’t designed properly, then an irrigation controller cannot be programmed properly," added Dave Shane, Mid-Atlantic area specification manager, Rain Bird Sales, Tucson, Ariz. "In this case, before installing a system, a contractor may recommend the customer have his or her landscape reinstalled based on zones."

Then contractors need to take into consideration whether the plant material is new or mature because the difference means different watering requirements, Kah said.

"Newly installed plant material will need more water more frequently," Kah recommended. "Typically, more mature trees and shrubs can survive longer durations in between waterings because they have a well-established root system and can gather water from a larger area – not just the first 8 to 12 inches of the soil."

Properly grouping plant material and determining its age can help a contractor then figure out how the weather, sunlight, sloping areas and shade or wind will affect the material and water it accordingly.

SOIL CONDITIONS. Since overwatering is just as big of a problem as underwatering, contractors need to make sure they know the facts about soil type and infiltration (how quickly the soil accepts the water) on the landscape being irrigated to prevent fungal growth and plant disease, Gordon stressed.

The more dense the soil, the better it holds moisture, Kah stated.

"Soil with a lot of clay holds moisture well and can be watered less frequently to prevent runoff while sandy soil doesn’t hold moisture well and should be watered more frequently," Kah explained.

Runoff occurs when the soil won’t accept all of the water applied and the excess water puddles up on top of the soil until it runs off into the sidewalk or another area of the landscape. This can be a problem with clay and rocky soils, said Joe Cortopassi, vice president/general manager, Green Turf Irrigation, St. Louis, Mo.

To determine the maximum amount of water needed before runoff occurs in a zone and to calculate the appropriate run time for a particular zone, Michael Schmitt, chief technical officer, WaterWise, Calabasas, Calif., suggested a contractor turn on a zone and use a stop watch to measure how many minutes of water the zone needs before runoff occurs.

Another way to avoid runoff, Kah said, is by calculating precipitation and evapotranspiration (ET) rates to determine how much water was lost in a particular area so it can be replaced accordingly.

COMMERCIAL VS. RESIDENTIAL. Despite obvious acreage differences, programming an irrigation controller for a commercial property is different from programming a controller for a residential property.

On a residential property, usable turf needs to be a consideration, according to Gordon.

"A contractor doesn’t want to program an irrigation controller to run on a Friday or Saturday so that the turf is soggy on the weekend," Gordon explained. "Homeowners want usable turf, particularly on the weekends. Contractors need to be considerate of their customers’ lifestyles when programming the controller while at the same time meeting the landscape’s watering needs."

On a commercial property, there are more stipulations to be aware of and the watering window is limited, remarked Cortopassi.

"Commercial accounts usually don’t want the irrigation system running during business hours because of runoff and because they don’t want vehicular and foot traffic affected by the irrigation system’s schedule," Cortopassi explained.

This can be a challenge, especially when on a commercial property a contractor may not be dealing with an in-house maintenance manager who can monitor the system daily.

"A problem can arise in the early spring or late fall in some areas where cold snaps sneak in and can freeze water left in the pipes," Cortopassi said. "The reason for caution is because if an employee or customer of that commercial client comes walking up the sidewalk and slips on ice caused by runoff water that froze from the cold, then a lawsuit could ensue."

"On commercial properties, the general rule is that the irrigation program needs to be scheduled during the watering window and the hardscapes need to remain dry at all times," Gordon added.

To avoid problems like runoff, drip or subsurface irrigation is often used on commercial properties, particularly glass buildings, according to Cortopassi, because it runs on an hourly basis, doesn’t affect traffic and isn’t affected by wind, therefore water isn’t carried away by a gust of wind to spray the glass windows of the building or the hardscapes surrounding it.

Residential properties can also utilize drip irrigation for plant material that needs watering at the roots and not on the leaves, such as rose bushes, Cortopassi said.

AFTER INSTALLATION. After a system is installed, a contractor’s work isn’t finished, according to Schmitt.

"Maintenance contractors generally include the monitoring and adjustment of controllers as part of their services," Schmitt explained. "Installation contractors are told how long they are to maintain the site prior to turning it over to the owner. Programs should be adjusted as often as possible. At a minimum, I would recommend weekly updates to the controller program, generally immediately after a mowing."