One of the few palms native to North America, the California fan palm Washingtonia filifera is a species often found in the in the desert areas of California, southwestern Arizona, and the northern regions of Baja California. The tree receives its name not only from its native area, but also from the fact that the leaves are shaped like fans, which is known as a palmate frond. The California fan palm is often grown as an ornamental tree in warmer locations, but can also grow wild, especially along alkaline waterways.
The California fan palm's adaptability makes it a popular choice for many landscapers, home and business owners. The tree prefers slightly alkaline soils in its natural habitat, but it can also thrive in neutral or slightly acidic soils as well. The California fan palm, which is often found in deserts, is also very tolerant of dry conditions, making it a good choice for those living under irrigation or water restrictions. The California fan palm does not shed its fronds often and produces very few litter problems with fruits, making it a very low maintenance species in that regard as well.
One of the key requirements for California fan palms is simply to make sure they have enough light. The trees prefer full sunlight, and this is especially important for younger trees as they try to establish themselves. Some pruning of dead fronds is also helpful for younger trees so that they do not become too top heavy while establishing a root system.
The trees are considered to grow at a moderate pace and are capable of reaching heights up to 60 feet (18.28 meters). This fact makes them unsuitable for use as indoor house plants, though they may be used as a centerpiece in outdoor patios. The diameter of the California fan palm trunk can be as large as three feet (91.44 cm). Thorns are limited to the fronds, which makes the trees suitable for yards with children and pets, especially if they are already mature trees.
The trees are grown in USDA zones 8 and higher, making them one of the more versatile of the palm species. They are able to withstand temperatures as low as 15 to 20 degrees Fahrenheit (-9.4 to -6.7 Celsius), but some foliage damage will occur. In cold conditions, the leaves may lose some of their green color, but quickly rebound with the return of warmer temperatures. They typically live at elevations under 1,000 feet (304.8 meters).
While the California fan palm is not considered a tree that is important agriculturally, its fruit is edible. Many animals may feed on the nuts it produces after they drop. The Cahuilla Indians, who lived in Southern California, ate the fruit, ground it as flour and used it to make beverages.