What is Washingtonia?

Washingtonia is a genus of palm trees found in the desert regions of the Southwest, spanning across several US states, as well as northern Mexico. There are only two species in this genus, W. filifera and W. robusta and both are widely cultivated as ornamentals in their native region. These trees are known by a number of common names, including Washington palm, California fan palm, Mexican fan palm, and petticoat palm. People interested in cultivating them can find specimens at a nursery or garden supply.

These trees are adapted for water deposits in desert regions, such as the moist soil found around some desert canyons. They prefer full sun and medium-rich, well-drained soil that retains moisture well. They thrive in United States Department of Agriculture (USDA) zones nine through 11, and while they can be grown in cooler regions, they are very frost sensitive, and will die off if not provided with adequate protection from frost.

Washingtonia species produce single tall gray trunks that develop distinctive leaf scars over time as the trees grow. At the top of the tree, a cluster of fan-shaped leaves topped with hooked spines develops. As the leaves die off, they tend to sag against the trunk and hang against it, creating a “skirt” of dead leaves. In some municipalities, people are required to trim their Washingtonia palms to remove the dead leaves, as they can become a fire hazard in addition to being attractive to pests like rats and termites.

These trees produce edible fruit, once used as a food source by Native Americans. Some communities still use the fruit to make jams, jellies, and fermented drinks. Washingtonia can also be used for thatching and other building supplies. In regions where natural building materials are used, people may regularly trim the trees for foliage to use in thatching and other projects. A common setting for Washingtonia palms is along a boulevard or avenue, where the trees can be planted in stately rows for visual effect and privacy.

Washingtonia filifera has a more northern range and will resist cooler temperatures better than W. robusta, an important factor to consider when selecting a species for cultivation. Both species can be transplanted as mature trees, allowing people to bring mature trees into a landscaping scheme to give it a more finished look. However, adult trees tend to be substantially more expensive than younger ones, and the costs of moving a fully mature tree can also add up quickly.