By Warren Tenney
More than half the drinking water used in the Phoenix Metro area is used outdoors, mostly to irrigate landscapes. Desert dwellers irrigate a variety of plants, trees and grass all year long as the weather swings from extremely hot to freezing. Establishing a lovely landscape can mean a steep and expensive learning curve. It doesn’t have to. There are two important and easy lessons to maintaining a pretty and water-efficient yard in the desert. First, understand how much water your plants, trees and grass need to thrive. Second, learn to set your automated irrigation controller so it waters for maximum health, beauty and efficiency. AMWUA cities offer homeowners free classes, publications and videos to help.
The efficiency of an automated irrigation controller is directly related to the competence and knowledge of the person setting the controls. To keep any established desert-adapted landscape thriving the controller needs to be set to water infrequently but deeply. People who are not used to daily sunshine eagerly water their trees, cactus and shrubs a little every day. It’s a common practice that wastes water and threatens the life of any landscape. For example, you can program your controller to water your grass 15 minutes every day and your grass will stay green. The problem: you could be using two and half times the amount of water your grass needs to thrive. You can water your tree 15 minutes every day but frequent, shallow watering means your tree will never grow roots deep enough to stand up to monsoon winds. Here are general watering rules that help. AMWUA has links to more complete watering guides.
- Water once a month in the winter, once every two weeks when temperatures begin to rise in the spring, and once a week in the hottest and driest part of the year, usually late May until the monsoon brings rain and higher humidity in early July.
- When you do water, water to a depth of 3 feet for trees, 2 feet for shrubs, 1 foot for smaller plants and a half foot for grass. (You can measure the depth of your watering with something as simple a wooden stick.)
The second step is learning to adjust an automated irrigation controller to match what you’ve learned. Typical controllers are not difficult, but they can be confusing at first. People can’t tell the difference between station A and program A and don’t want to deal with it. They set it once and forget about it or leave it up to a landscaper. Watch the manufacturer’s how-to video designed for your controller. Then you can set it yourself and save water and money. Irrigation specialists recommend re-programming a controller at least four times a year to match the seasonal needs of your landscape.
Newer automated irrigation devices are known as smart controllers. If programmed correctly, these controllers adjust for seasonal changes on their own based on weather data. This technology has been used to irrigate city parks, golf courses and farms for decades. Now this technology is being perfected for back yards.
Some of these controllers adjust themselves according to historical weather patterns and an onsite temperature sensor that’s part of the control box. Many of them come with rain gauges attached or ones that you can add. Other types of smart controllers use a manufacturer’s cell phone modem to attain current weather conditions. These controllers are more precise but require a monthly subscription fee.
The latest smart controllers use your home’s Wi-Fi connection. They allow you to program and adjust them from an app on your cell phone and connect to the closest weather station for daily meteorological conditions. These controllers are easier to use but need more initial input to set up. Owners are asked to answer questions such as kind of plants being watered, type of soil (clay loam in central Valley, sandy loam in higher, northern parts of the Valley), sun exposure, sprinklers or drip, and slope. The manufacturer’s videos help answer these questions.
You can find smart controllers that include soil sensors. These soil probes let the controller know exactly how much water is in the soil. Due to mixed landscapes – with different trees, plants and grass – and different sun exposures these can be more challenging to configure.
Some cities will offer homeowners, HOAs and businesses rebates for installing new WaterSense approved smart controllers. Residents can make an appointment with the Town of Gilbert’s irrigation specialist to come to your home and help you set a smart controller. One precaution: When buying any smart controller make sure it allows you to do more than just adjust run times. These types of smart controllers are made for other climates and will not water long enough in the winter to reach the roots of your trees and plants. Desert yards require a smart controller that adjusts both run time and frequency (or how many days between watering). This allows you to adjust the controller to meet the needs of desert-adapted landscapes by programming to water deeply all year but less often when it’s cooler.
Right now, AMWUA cities are offering free landscape classes about watering and irrigation systems. These classes can make maintaining a lovely and water-efficient yard far easier.
For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.