The Mexican fan palm or botanically Washingtonia Robusta [Washing-ton-ee-a, roh-BUS-tuh] is a flowering species from the Arecaceae or the palm family.
Contrary to what the plant’s scientific name suggests, the palm species are not native to Washington or the United States.
It is, however, named after the US President George Washington and has also been naturalized in some parts of the country.
Washingtonia Robusta is native to Baja California Sur and western Sonora in north-western Mexico.
But, as mentioned above, it has also been naturalized in some other parts of the world.
These include Texas, Southern California, Los Angeles, Florida, Hawaii, Italy, Lebanon, La Réunion Island, Spain, and some parts of the Canary Islands.
The plant is also cultivated in Arizona, New Mexico, South Nevada, Florida, South Georgia, coastal areas of South Carolina, and extreme southern areas of North Carolina.
Since it is native to Mexico, the plant is generally known with the following common names:
- Mexican washingtonia
- Mexican fan palm
- Skyduster (due to its huge size)
Washingtonia Robusta Care
Size & Growth
Mexican fan palm has a fast growth rate, typically reaching the height of 80’ feet tall.
However, it sometimes grows even higher; up to 98’ feet.
The plant is referred to as fan palm because its leaves, comprised of multiple small leaflets and a long sharply-toothed petiole, form large palmate fans.
The leaves are green with a reddish-brown split base.
When grown under the right conditions, the plant forms a full round canopy of green fronds.
The leaves grow on a long, erect, branchless, and slender trunk, with a little wider base.
The trunk initially has a reddish-brown color, but it changes to gray as the plant grows up.
Mexican fan palm tree is also known to have a very long life and can potentially live for decades.
Washingtonia robusta and Canary Island Date Palms are commonly seen lining many streets throughout San Jose, California.
Other Palms Found Growing with Washingtonia:
Flowering and Fragrance
The plant produces very long pendulous inflorescences, form between the leaves, in the spring.
They grow up to 9.8’ feet and bear numerous small pink to pale orange flowers.
Flowering is followed by the production of small, round, blue-back drupes in the summer.
The fruits are thin-fleshed and edible.
Light & Temperature
Washingtonia robusta grows best in full sun but can tolerate part shade.
Washingtonia robusta is quite winter hardy, but a little less resistant to cold weather than its close relative Washingtonia filifera (W. Filifera California fan palm).
It can tolerate temperatures down to 18° degrees Fahrenheit (-8° C).
The plant is hardy to USDA hardiness zones 9 to 11.
Watering and Feeding
Although washingtonia robusta is considered a desert palm, it naturally grows in areas with permanent surface or subsurface water.
This means it doesn’t have high drought tolerance.
Water the plant moderately in all seasons, except winter – keep it almost dry in the cold weather.
Feed the plant with a controlled-release fertilizer every other month, during the growth phase.
Soil & Transplanting
Mexican fan palm easily grows in a wide range of soil types but thrives in fertile soil.
Make sure the soil is well-draining because the plant cannot tolerate soggy or water-logged soils.
The plants are easy to transplant but only do it if necessary.
The young plants (under seven years old) may need to be transplanted once in two years and the young adult trees (between 7 to 15 years of age) may need transplantation once in three years.
While the plant’s transplant throughout the year, spring and summer are the best times to do it.
Grooming and Maintenance
The young palm trees need some grooming and maintenance as they do not automatically shed their old leaves.
The old dead leaves continue to hang around the trunk, creating the hula-skirt effect the species is known for.
While it is one of the most distinguishing characteristics of washingtonia robusta, the leaves, unfortunately, cannot be left hanging for long because they are a fire hazard.
The dried leaves also often serve as the home for many undesirable creatures, such as rats, so it is better to prune the plant to remove the dead fronds.
The plant, however, typically starts to shed old leaves itself once it grows up to 30’ feet, which means large palms do not need to be pruned.
How to Propagate Mexican Fan Palm
Mexican palm are easily grown from seeds.
When kept under uniformly moist and warm conditions, between 85° to 95° degrees Fahrenheit (29° – 35° C), the seeds typically germinate within two weeks.
Mexican Fan Palm Pest or Diseases
While the Mexican fan palm isn’t highly susceptible to diseases, it can encounter a few problems due to potassium deficiency.
These include lead discoloration, leaf tip necrosis, and even premature death of some leaves.
However, unlike with many other plants, it is recommended to not remove the partially necrotic or discolored older leaves as they serve as a source of potassium for the plant.
Excessive watering or poorly-draining soil can lead to root rot and decay.
The plant may get affected by scale insects and glasshouse red spider mite.
The seeds of washington palm are dispersed by birds, air, or water.
Washingtonia Robusta Uses
Mexican fan palms are grown as ornamental plants, mostly in commercial or public open spaces and as street trees because of their huge size, which makes them unfit for most residential landscapes.
They particularly make great displays when against high-rise buildings and alongside boulevards, when planted in groups and at equal intervals respectively.