Days are getting shorter and cooler, so plants require less water.
Irrigation of desert adapted and native plants can go to once a week starting
in late October. For well-established native plants (at least 3 years old) you
can back off to twice a month.
There is one caveat to this, however. The only way you can change your
watering schedule is if you have been watering correctly from the start. This
means deep watering so the entire root system gets a good soaking. If you have
been engaged in shallow watering, the root system will not be as drought
tolerant, and the plant may show signs of stress if you back off.
So how to change this? Start watering your plants deeply and slowly, and
over a growing season (through next summer) you will be able to adjust your
irrigation in the winter months to save water. The truth is, a vigorously
growing landscape plant is not happier. Studies have proven moderately stressed plants, plants that
are not watered and fertilized regularly, are less prone to insect pests and
disease.