Aug 17 2015Share

Watering: Every Desert Landscape's Beauty Secrets Revealed

By Kathleen Ferris

So you've selected desert-adapted plants and trees and installed a beautiful water-saving landscape.

The key to maintaining your landscape's health, beauty, and longevity is watering correctly. Getting the watering wrong is the most common cause of plant failure in the desert. Not surprising, really. Watering desert landscaping is a bit of a mystery.

We have the solution.

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Landscape Watering by the Numbers is an interactive website that completes the trio of gardening guides that include Landscape Plants for the Arizona Desert and Landscaping with Style created for Valley homeowners, nurseries, and landscapers. (Find all three guides along with additional resources, demonstration gardens, free classes, professional assistance, and rebate information available at

Here are some of the questions the watering site can answer:

  • How many gallons of water does a tree, shrub, ground cover or cactus need and how often does it need it? (Hint: There’s a simple chart.)
  • How do I know if I’ve watered a plant deeply enough? (Hint: A piece of rebar or a long screwdriver can tell you.)
  • Where do I place the drip emitter? (Hint: Don’t water at a tree’s trunk, the roots stretch as far as the canopy and beyond.)
  • How long should I water to make sure a plant or tree is not over or under watered? (Hint: There’s an online calculator that will do the math for you.)

Want more details? Check the upper right corner of the pages of Landscape Watering by the Numbers. There is a long and helpful menu of frequently asked questions that gives you more tips. Here are a few examples:

  • Water outdoor potted plants more frequently because they have less soil and a restricted root system.
  • Leach salt from your soil to avoid leaf burn by watering twice as long as needed two times each summer.
  • If water is running away from your plant, water only half the calculated time. Then wait an hour before finishing the cycle.

In the mid 1990s, AMWUA developed a postcard-size plastic chart to place inside an irrigation control box. It was a rough outline for setting watering times.

Water conservation experts from the cities of Mesa and Scottsdale led a team that created the 18-page book. More than 900,000 copies have been printed since it was published in 2002. Two years later, Landscape Watering by the Numbers became an interactive online site on Water—Use It Wisely. Water—Use It Wisely is a water awareness campaign initiated by the City of Mesa and supported by AMWUA and other partners across the state. You'll also find a guide to wisely watering your lawn. You can get a free copy of the watering guide from your city’s water conservation office or at many local nurseries.

Now, here’s the last key thing to remember about desert landscaping and why the information offered by Landscape Watering by the Numbers is so important: It’s not the desert garden that saves water, it’s the desert gardener.

For 46 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

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