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As you probably already know, different types of plants require different amounts of water. A Kentucky bluegrass lawn, one of the thirstiest and most common plants in Utah landscapes, about 25 inches of water per year. Trees, shrubs and many other plants usually require significantly less.

Knowing the water requirements of the various plants in your landscape and grouping them together in the same irrigation zone ("hydrozoning") is the most efficient way to irrigate your landscape. Click on the links below to learn more about the watering requirements of your plants and why you should group them together:

Flowers and Ornamentals

Annuals and bedding plants generally donít have time to develop a sufficient root system before the season is over. Because of this, annuals usually require about the same amount of water as your lawn.

This situation represents a scenario for hydrozoning. Because these flowers and your lawn require approximately the same amount of water, it is permissible to group annual or bedding plants on the same irrigation zone as your lawn.


Trees and Shrubs
Did you know that most trees and shrubs require about half of the water of your lawn? Over-watering your trees and shrubs can promote disease and shallow rooting, causing major maintenance problems in the future.

In addition to needing less water, trees and shrubs should be scheduled at a different interval. Trees and shrubs naturally have deeper roots than your lawn. Watering for a longer amount of time, but less times per week, will help water get all the way into the full root zone of your plants. This watering method promotes healthier plants and a deeper root system.

Perennials and Xeriscaping
One characteristic of many perennials and Xeriscape plants is their deep rooting system. These types of plants have evolved to endure from year to year, and have thus established an extensive and deep root zone.

In order to water your perennials and Xeriscape plants efficiently, watering should be deeper and less frequent--similar to a schedule for trees and shrubs, but shorter run times and more frequently.

Putting grass and trees on the same irrigation zone will cause you to over-water your trees, and could lead to disease and other problems caused by excess water. Because water is not reaching the extent of the root zone for the trees, this watering pattern promotes shallow roots which could cause extensive landscape damage.

A general concept to remember is that you want to increase the run time and decrease the interval between watering as the root depth of the plant type gets deeper. The following graph is a conceptual representation of this concept:

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Conservation Tip

Perform an annual maintenance check on your evaporative (swamp) cooler. Check for and fix any leaks you find.

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