Q: This past October I planted three Palo Verde "Desert Museumโ trees which were in 10-gallon containers.ย Also a Texas Mountain Laurel which I previously emailed you about, and a Pyracantha and some Lantana. We depart for the summer on April 14. I plan to set up an irrigation system. Can you advise me as to the size and number of emitters per tree, frequency of irrigation, and duration of irrigation?
A:ย The number of emitters is based on the size of the tree so if your trees are seven to 10 feet in diameter, for example, you would use about four emitters that can deliver about three gallons per hour. If your trees are larger you can add a couple more emitters every four or five feet in diameter larger.ย The emitters should be placed in a circular fashion at the edge of the crown of the tree or shrub.ย For desert species like the palo verde, watering every 14 to 21 days in the summer to a depth of 24 to 36 inches is best.ย In the winter you shut off your irrigation for desert species unless we get no winter rain. The pyracantha will likely need more frequent irrigation, more like every week in the summer, and will still benefit from water every three weeks in the winter.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. ย Questions may be emailed toย tucsongardensage@gmail.com
