Q: I have a question about our magnolia trees. It appears that one is dying and I am wondering if that is because the grass below them was removed. When the grass was there, the trees were very lush. Since the grass was removed and the ground covered with rock (and no water), it has changed the life of the magnolias.
A: I think you answered your own question. The tree was possibly receiving significant water from the grass irrigation. The fix for that would be to set up an irrigation system for the trees. A drip system arranged in a circular fashion around the drip line of the tree would be ideal. Non-native trees like the magnolia should be receiving 24 to 36 inches of water every two to three weeks in the winter. In the spring and fall, increase the frequency to 10 to 21 days and in the summer every seven to 14 days.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions and photos may be emailed to firstname.lastname@example.org