Willow Acacia (Acacia salicina)
Sleek, fast-growing, and fully at home in the peak of Phoenix heat, the willow acacia is a fantasticaly low-maintenance tree option for western afternoon shade screens including narrow spaces between buildings.
Mature Canopy Size
20–30 ft tall, 15–25 ft wide — upright, willow-like form with softly drooping branches
Growth Rate
Fast — 2–3 ft per year in warm seasons
Water Requirements (Minimum vs. Maximum Growth)
Minimum: Low — deep watering every 2–3 weeks once established
For Maximum Growth: Weekly deep irrigation during summer creates faster canopy formation and denser shade
Ecological & Functional Benefits
Excellent desert shade tree with minimal litter
Nitrogen-fixer — improves soil for companion plants
Attracts pollinators with small, fragrant cream-colored flowers in spring
Strong visual appeal due to its elegant, weeping shape
Effective rapid re-greening species thanks to its root sprouting
Edible / Harvest Season / Nutritional Benefits
Not edible for humans — pods provide wildlife forage
Minimum Chill Hours
None — fully adapted to arid, low-elevation climates
Maintenance Requirements
Low to moderate — occasional pruning to thin canopy and reduce wind resistance. Relatively clean tree but can drop pods after flowering. Note that this tree pushes new root sprouts around itself and these will need to be kept under control unless you want a forest of willow acacias!
Thorny or Not?
Almost always thornless — rarely you can find some hybridized varieties with small, inconspicuous prickles
Deciduous or Not?
Evergreen to semi-evergreen — retains most foliage year-round in Phoenix
Root System
Deep, moderately spreading root system
Typically non-destructive, but large roots can lift nearby pavement if overwatered
Safe near walls and patios with 10–15 ft spacing
Benefits from deep, infrequent watering to encourage stable rooting
Native Range
Native to Australia, where it grows along dry creek beds and arid woodlands. Introduced to the American Southwest for its drought tolerance and graceful form.
Miscellaneous Notes
Commonly confused with desert willow (Chilopsis linearis) due to name and shape, but unrelated
Fast, reliable shade tree for desert yards and streetscapes
Handles reflected heat and compacted soils better than many natives
Pairs beautifully with lower desert plantings like agave, lantana, and desert spoon
Questions about the Willow Acacia?
Comment below or on our social media pages @permascaping.
