Even Xeriscapes need water sometime – especially when they are first getting established. Three factors are critical in irrigation: frequency, timing and amount of water. Watering your Xeriscape can be done at almost any time during the day, but early morning is the most effective time to irrigate due to reduced evaporation. It is also better to provide your plants with water before mid-day when the evaporation rate is the highest.
Watering in the evening can also be done, but may favor disease development, particularly under cool night temperatures. Most disease-causing fungi require several hours of leaf wetness for infection and disease development to occur.
Plants that require water will exhibit various symptoms including wilting, browning, and drying out. Disease, pests, poor soil, overly rich soil, too much water, or physical damage to the plant may also cause these symptoms. More water is not always the answer, but it’s not a bad first guess.
Your watering patterns should change as the season’s change. Your Xeriscape needs a lot less water in April or May than it does in July or August. If you have an automatic irrigation system you should adjust your clock monthly to account for seasonal variations. Depending on where you live you need to make smaller or larger adjustments.
Home Xeriscape plants require no additional water beyond rainfall. Others will require regular (albeit infrequent) water, perhaps once of maybe twice per week. Many Xeric plants will only need supplemental water only during the hottest and driest periods of the year and the rest of the time can survive on rainfall and retained soil moisture. If you have grouped your plants by water needs it should be easy to adjust your watering schedule according to the requirements of each plant grouping.