The Mexican Fan Palm - The Washingtonia Robusta
Background & Geographical Spread
The Mexican Fan Palm, also known as the Washingtonia Robusta (scientific name), Washington Palm, or the Petticoat Palm, is a member of the Arecaceae Family. Known for its ease of growth, the Mexican Fan Palm is a classic resort style palm tree that has a wide variety of landscape applications. With a relatively small natural habitat limited to the river banks of a few canyons located in Sonora and Baja, these Southern California icons are perhaps one of the most commonly planted palm trees around the world. This relatively scarce palm tree became one of the most widely grown palms throughout the world because of its hardiness, ability to live in a variety of soils, and fast growth rates. They can now be found in Hawaii, Japan, Alabama, Arizona, Arkansas, California, Georgia, Louisiana, Mississippi, Nevada, Oregon, Texas, other countries surrounding the equator.
Frond, Fruit, & Height Information
The Mexican Fan Palm is commonly seen at heights of 40-50 feet, but some specimen palms can grow up to 70-100 feet. They can grow up to 4 feet per year, but are more likely to grow 2 feet per year under normal gardening conditions. The frond Spread is between 12-15 feet and the fronds form a crown that is slightly taller than it is wide. A healthy Mexican Fan Palm Crown should have about 30 leaves, and can produce up to 50 leaves per year, but Potassium (K) deficiency typically reduces the number to approximately half or less than that number. These fronds are attached to the trunk of the palm tree with sharply barbed petioles of about 4-6 feet long, and the evergreen fan shaped fronds feature hanging leaflet tips. The fronds persist on the tree after they die forming a dense, brown, shaggy covering, or “Hula Skirt” below the crown, and is how the Mexican Fan Palms got the name the Petticoat Palm. This skirt can be a fire hazard, and can host a variety of wildlife such as: birds, snakes, rodents & insects. The palm also produces a white or creamy flower and small, round, black fruit of about ½ inch in diameter that sticks out beyond the limit of the crown. The fruit does not attract much wildlife, but birds will eat the fruit and seed and propagate the palm. We suggest removing the skirt, fruit, and flower in urban settings.
Trunk Description & Hardiness
The trunk of the tree is slender, solitary, and slightly curved. The trunk of the Mexican Fan Palm tapers from nearly two feet in diameter at the base to as little as eight inches near the crown of older specimens. The trunks are reddish brown in color, but weather to a light gray over time. Ring scars remain where dead leaves have been removed.
Mexican Fan Palms are known for their Hardiness. They are salt resistant, drought tolerant, resist pests easily, and can live in a variety of different soil types including sand, clay, and loam. It is important to note that these palms are not as drought tolerant as many people think due to their riparian (dwelling on the banks of a river) origins, and the soil must drain for the tree to do well. Too much water can lead to root rot. The Mexican Fan Palm is tolerant to a wide range of PH as well. Soil that is not too acidic is preferable, and the palms are able to grow in extremely alkaline soils.
Hybridization Between The Mexican Fan Palm and the California Filifera Fan Palm
The Mexican Fan Palm hybridizes with the Washingtonia Filifera, or the California Fan Palm. However, the Mexican Fan Palm is better suited for the east coast. Overall, the Mexican Fan Palm is more suited to moister climates while the W. Filifera is a true desert species that is more resistant to cold snaps provided conditions are dry. It is thought that the hybrid between the Mexican Fan Palm (the Washingtonia Robusta) and the California Fan Palm (the Washingtonia Filifera), the Filibusta, should grow fairly well in cooler climates with wet winters, combining the moisture resistance of the W. Robusta and the W Filifera. Examples in the United States include Oregon and Washington. There is a lot of misconceptions about palm tree survival and plant hardiness. We suggest reading David A. Franckos “Palms Won’t Grow Here and Other Myths: Warm-Climate Plants for Cooler Areas” to help guide you in incorporating palms and other species into your garden or landscape.
Palm Tree Maintenance & Trimming
The main thing that somebody purchasing the Mexican Fan Palm will need to keep in mind is tree trimming. Once a tree gets taller than around 25 feet a professional tree pruner is needed to remove the old fronds. We suggest trimming the Mexican Fan Palm in late spring or early summer just after the tree has produced its fruit and flower. This will get the trimming done and remove the fruit or flora at the same time, eliminating the seeds from scattering the floor of your landscape. Neglecting to remove the flower stalks will result in volunteer palms showing up near the parent tree. We advise all of our customers to be mindful of how they trim their palms. It is common practice to over-prune the Mexican Fan Palm, leaving just a few fronds in the crown. We highly discourage doing this. Trees that are repeatedly pruned in this way will lose their vigor and the upper trunk can become spindly such that the crown dies or breaks off in high wind. Therefore: we suggest leaving at least 50% of the green fronds intact.
Once the palm reaches 30 feet in height they typically drop their old leaf bases within a year or two. Once this occurs, the tree becomes “self-cleaning” and do not require manual removal of old leaves. However, there will be dead fronds persisting at the crown until they fall during that one to two year period.
Few nutrient problems occur in the Mexican Fan Palms, but potassium deficiency is virtually ubiquitous in this species, where it causes leaf discoloration and premature death of the oldest leaves. Avoid removing discolored leaves as the tree is able to drain potassium out of them when sources of potassium in the soil are insufficient. The only other deficiency that is likely to be encountered is a boron deficiency which causes small, crumpled new leaves to be produced. With that said, as far as fertilizer is concerned, consider supplementing with Potassium (K) and Boron, and lower water usage once the tree is established. Lastly, a common disorder of Mexican Fan Palms is an erosion of the outer portion of the trunk. Although some people believe that water from irrigation heads causes this problem, it also occurs on palms that do not receive irrigation.
Overall, the Mexican Fan Palms can easily give your garden or landscape a tropical, resort-like feel. This fast growing, salt resistant, cold hardy palm is an excellent choice for beaches and coastal areas. The Mexican Fan Palm can make a dramatic statement in larger landscapes and a natural touch to multi-storied homes. This palm tree is ultimately ideal for large properties, along streets, and to add vertical effects to any garden. The Mexican Fan Palm often grows out of scale in most landscapes with one-story buildings, and we therefore recommend incorporating other tall trees with them. Some examples include: Melaleucas, Oaks, Carolina Cherry’s, Date Palms, California Fan Palms, Palo Verdes, Eucalyptus trees, and a variety of Succulents and desert shrubs. Finally, we recommend highlighting their grand statuesque appearance with landscape night lighting. We grow small to large Mexican Fan Palms on our farms. So give us a call if you want us to help turning your home into a tropical resort!