Although desert plants have developed mechanisms for conserving and storing water, none have given up the need for water entirely.  There are many variables that determine how much and how often plants need supplemental water. 

SOIL:  Soils with a high clay content hold moisture well, too well for some desert plants, and could be amended with a small amount of organic matter and coarse sand.  Rocky soils hold little moisture so plants growing in them require more frequent watering. 

TEMPERATURE:  Most desert plants grow when it is warm. Active growth coupled with high evaporation rates means that more water is needed in warmer months.

AGE AND SIZE:  All plants, even desert plants, need more water when they are young and when they have been recently transplanted.

WATERING NEW TREES AND SHRUBS:  The following is a general guide to watering new plants.  For your own yard, take into consideration the soil, plant size and plant age.  Most importantly, watch the plants carefully.  If they wilt in the heat, begin to lose their leaves, or are not thriving, you may need to increase the watering.

Trees and shrubs (woody perennials) require regular, deep watering for the entire first year that they are in the ground. This is true regardless of the size of the plant when it was transplanted. In the cooler months, natural rainfall may supply sufficient moisture for most woody plants.

WATERING SCHEDULE:  SHRUBS
TEMPERATURE	1ST YEAR	2ND YEAR	AFTER 2 YEARS
Over 108 degrees	every other day*	every 3 days	once a week
Over 100 degrees	once a week*	every 10 days	every 2 weeks
90 – 100 degrees	every 10 days	every  2 weeks	every 3 weeks
75 – 90 degrees	every 2 weeks	every 3 weeks	every 4-5 weeks
Below 75 degrees	every 3 weeks	every 30 days	every 4-5 weeks

*Small plants, such as those from 1-gallon containers, need to be watered twice a week when temperatures are over 100 degrees. When temperatures are over 105 degrees, keep a close watch on newly transplanted plants. Smaller plants may need to be watered every day, or at least every other day.

WATERING SCHEDULE:  TREES
TEMPERATURE	1ST YEAR	2-5 YEARS	AFTER 5 YEARS
Over 108 degrees	every 2-3 days	every 10 days	every 3 weeks
Over 100 degrees	once a week	every 10 days	gradually extend   intervals between   waterings to 4 weeks
90 – 100 degrees	every 10 days	every 2 weeks	gradually extend   intervals between   waterings to 6 weeks
75 – 90 degrees	every 2 weeks	every 3 weeks	water if no rainfall for 45 to 60 days
Below 75 degrees	every 3 weeks	every 30 days	water if no rainfall for   60 days