Tree · Sonoran native
California Fan Palm
Washingtonia filifera · Arecaceae
Also called: Desert Fan Palm, California Washingtonia, Petticoat Palm, Arizona Fan Palm
California Fan Palm (Washingtonia filifera) is a low-water tree native to the Sonoran Desert region well suited to Tucson and the low desert. It thrives in full sun.
California Fan Palm at a glance
- Water use
- Low (established)
- Sun
- Full sun.
- Mature size
- 40-60 ft H x 15-20 ft W (stout trunk, large robust crown).
- Growth rate
- Moderate (slower than W. robusta).
- Bloom
- Creamy white flowers on long arching inflorescences., Late spring to early summer; small black date-like fruits follow.
- Cold hardiness
- USDA zones 8b-11; the hardiest Washingtonia, tolerating brief lows near 10-15 F when dry.
- Soil
- Tolerates sandy, rocky, and alkaline desert soils; salt tolerant with good drainage.
- Native range
- Native to desert oases and spring-fed canyons of the Sonoran/Colorado Desert in California, far western Arizona, and Baja California—the only palm native to the western U.S.
- Best used as
- Native specimen / oasis palm, Desert and naturalistic landscapes, Wildlife and habitat plantings, Street and park palm
- Wildlife
- Fruit is a key food for birds (and historically for native peoples); the dead-frond skirt shelters bats, birds, and other wildlife.
- Toxicity
- Non-toxic; fruit edible. Sharp petiole teeth can cause cuts.
How to grow California Fan Palm in Tucson & the low desert
Watering
Very drought tolerant once established; naturally restricted to seeps and oases, so deep monthly summer irrigation produces a fuller crown. Established trees survive on little supplemental water but grow slowly when dry.
Fertilizer & nutrients
A palm fertilizer with potassium and magnesium once or twice in the growing season prevents older-frond yellowing; add iron/manganese in highly alkaline soil.
Pruning & care
Remove dead fronds and old fruit stalks; the thatch 'petticoat' of dead fronds can be left (natural look and wildlife habitat) or removed for a clean trunk. Petiole margins bear stout teeth—wear protection.
Notes
The native, more cold- and drought-hardy fan palm—stouter trunk, larger gray-green crown, and conspicuous thread-like 'filifera' fibers between the leaf segments distinguish it from the taller, slimmer W. robusta. Better choice than W. robusta where a native, lower-maintenance, hardier palm is wanted.
Sources: Arizona-Sonora Desert Museum; University of Arizona Cooperative Extension; AMWUA Landscape Plants for the Arizona Desert; ASU Desert Plants database (C. Martin)