Xeriscaping: Watering Zones

In our part of the world, water use is a huge issue. Western gardeners need to take their garden planning one step further, and think of plant materials in terms of their water needs.

Many of our traditional garden trees, shrubs, and flowers come from areas of high rainfall, such as the eastern United States and Europe. They need more water than they will receive naturally in this area. In order to keep them healthy, we have to irrigate on a regular basis. This puts a strain on our limited water resources.

Little water, bright color
Little water, bright color

Instead of buying the same old plants, why not take advantage of our distinctive western climate and grow plants suited for Colorado?

Xeriscaping just means making efficient use of the limited irrigation water we have available. This is done by planting in watering zones. The concept is simple: different plants need different amounts of water to survive and thrive. Just as most familiar plants need constantly damp soil, many of our most beautiful and interesting Colorado species will rot if their roots are always wet.

In light of the recent drought, many people have started growing plants that need less irrigation. However, just adding low-water plants to an existing landscape doesn’t necessarily help. In order to take advantage of the many xeric plants now available, they must be grouped according to their water needs. Then the irrigation system can be adjusted to apply the correct amount of water to each area.

Agastache uses little water.
Agastache uses little water.

Most xeriscapes are divided into high, medium, and low water zones. A high water zone might include a small lawn and maybe those peonies that you just can’t live without. This area gets watered two to three times per week, depending on the weather.

Desert Columbine
Desert Columbine

The medium water zone receives supplemental watering perhaps once a week. Most areas planted with low-water shrubs and perennials would fall into this category.

Finally, the low water zone only gets watered during a drought. Once established, plants there are able to succeed on our average annual rainfall.

Note the “establishment clause”—it is critical that new plantings receive additional water until their roots have spread out into the soil and they can fend for themselves. That typically takes a year or two.

Future articles will cover other basic principles of xeriscaping, but in the meantime,  Colorado Springs Utilities offers lots of information.

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