Taking care of palm trees in Tucson

Palm trees are, generally speaking, not native to our desert. California and Mexican fan palms (Washingtonia filifera and W. robusta) could arguably be considered natives, but they grow only in very limited riparian areas in Arizona. They need more water than is generally available as rainfall and will require additional water in your landscape. They are also sensitive to cold, and need to be planted well in advance of winter so that their roots have time to establish. You can plant them from April through September in the Tucson area.

I like the look of palm trees in more groomed landscapes; they give a tropical feel and look stately. They are also relatively low litter, have non-invasive roots and don’t take up a huge amount of space on the ground which makes them good candidates for pool plants. Palm trees, even non-native ones, can provide habitat for wildlife. For example, birds like to roost in the canopies. In Agua Caliente Park, a family of owls has taken up residence in one of the palms, and has chicks there each year. Various insects and other small critters also like to hide out in the fronds. My date palm attracts various birds, particularly mourning doves.

Before planting a palm tree, make sure that your microclimate will support it. Some non-native palms are quite sensitive to cold, and if you’re in a cooler part of town they may not survive the most extreme winters. In town, however, it should be safe to plant most varieties. Make sure you check the palm’s hardiness before purchasing, however.

Despite their drought tolerance, palm trees grown in Tucson will require regular irrigation to a 2-foot depth. This is best delivered via slow drip irrigation; the duration will differ depending on the type of soil you have. You will need to check the depth of watering with a soil probe; for details on how to do that, check out this downloadable guide to watering. A palm tree planted in a lawn area will also need additional irrigation, because lawn watering schedules do not provide deep enough watering. As with a regular tree, the irrigation drippers will need to be moved out from the trunk periodically as the tree grows, eventually 4 feet away from the trunk.

Palm trees that have just been planted will probably need daily watering for the first week or so, enough to keep the root ball moist (but NOT soaking wet). After that, you can space out the watering slowly; once the tree is established (usually a year or so) it should do well with monthly deep watering in the spring and fall, every two weeks in the summer, and every four to six weeks in the winter. Again, however, the frequency will depend on the type of soil you have. Sandy soils will drain faster than soils with clay, and you don’t want your palms sitting in wet soil for any length of time.

If your palm tree is in a lawn area, make sure to keep the lawn away from the trunk. This is both to prevent moisture-related diseases on the trunk and to keep the trunk safe from damage with weed-whackers or similar lawn trimming equipment. Keep in mind that any damage to the trunk is permanent, and can cause diseases and insects to take hold in the trunk.

Palm tree fronds tend to turn yellow in our soils, chiefly because of low nitrogen. They also have a difficult time getting certain other nutrients like potassium and magnesium out of the soil due to the alkaline nature of our soils. For this reason, you should fertilize your palm tree about twice a year. The University of Arizona Extension office recommends fertilization with a palm-specific formulation in the spring and again in summer. This should keep them looking lush and green. Follow the directions on the label to avoid applying too much fertilizer, and water it in thoroughly.

Depending on the type of tree you get and your personal preferences, you may choose to prune your palm tree to remove dried fronds. Some HOAs require homeowners to keep their palms trimmed. Make sure you get a certified arborist to do this for you, particularly with taller trees. An arborist will know how to safely climb the tree without damaging the trunk, and will also (hopefully) know not to overtrim it. You should include this additional expense in your budget when planning for a palm tree.

Only dead fronds should be removed, and palm tree leaves should never be trimmed past the horizontal. Not only is this unsightly, it also risks permanent damage to the only area of growth at the top of the palm tree called the terminal bud. This area is very sensitive to mechanical damage, wind, frost, and the like. Aggressive trimming will potentially damage the terminal bud, and will result in an upside-down carrot look at the top of the palm tree. Once this happens, the palm tree is not only ugly, but is also forever damaged and at higher risk of dying from cold temperatures in the winter.

For lots of additional information about palm tree care, as well as a great overview of the species of palms you can plant in our area, take a look at Arizona Landscape Palms, a publication of the University of Arizona’s Extension office.