Q:Β We bought a blue Mexican fan palm at a local nursery four years ago in a 15 gallon container, it was fairly large β read expensive β and looked healthy.Β I was careful to dig a large planting hole and careful removing the plant from the containers. I put it on our drip. Today, four hours once a week with a two gallon emitter inserted in a 12-inch watering spike. So the water dispenses at the roots not the surface. It has continued to put on new fronds. However, for every new one that opens an old one withers. After four years, the plant is no bigger than the day we bought it. Fortunately, no smaller. But weβd had hoped it would become a substantial palm.
A:Β The Mexican fan palm (Washingtonia robusta) is well suited for our Arizona heat and is typically a fast grower. Most trees really take off in their third year after planting so you should have seen some significant growth in the past year at least. The possible issues that would prevent fast growth are insufficient water, fertilizer, and poor soil. We recommend watering every five to 10 days in the summer to a depth of 36 inches. In the spring and fall, water every seven to 10 days and in the winter, every 14 to 21 days. Drip emitters should be placed in a circular fashion around the trunk to distribute the water evenly to the roots. You can apply a slow release fertilizer around the root zone once each year. Planting holes should be twice as wide as the diameter of the container and deep enough that the root-shoot interface is about one inch below the surface of the soil. Since you didnβt specify, I wonder if the tree was planted at an appropriate depth.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Email: plwarren@cals. arizona.edu
