Yuma, Phoenix, Tucson and Flagstaff all made US News & World Report's list of the sunniest places in the U.S. While all that sun makes winter outdoor recreation a boon, it also means high cooling bills in the summer. Fortunately, low shade trees can help, reducing air conditioning use by up to 30 percent. Choose shade trees that tolerate the sunny, arid and often-hot conditions across the state.
Several trees in the acacia family (Acacia spp.) grow well in Arizona yards. Low-growing varieties include the leatherleaf acacia (Acacia craspedocarpa), a 10-foot-tall evergreen that creates light shade with its dense, gray-green foliage. Hardy in U.S. Department of Agriculture plant hardiness zones 8 to 10, the leatherleaf acacia blooms with yellow flowers in spring. Other low varieties include the sweet acacia (Acacia farnesiana) which reaches heights to 20 feet and has an airy canopy of blue-green, deciduous foliage. The sweet acacia grows in USDA zones 9 to 11 and blooms with aromatic orange flowers in late winter or early spring. Both acacias grow in full sun to partial shade and well-draining, alkaline soil.
Palo verdes add year-round color to the Arizona landscape with their signature green bark. Low selections include the palo brea (Parkinsonia praecox), a Sonoran desert native that grows to 20 feet tall. This sun-loving, drought-tolerant tree has smooth, green bark and flowers in spring with yellow blossoms. The palo brea is hardy in USDA zones 9 to 11. The "Desert Museum" palo verde (Cercidium x. "Desert Museum") grows to 25 feet tall and has fine, semi-evergreen foliage. It also blooms in spring and grows well in sunny, dry sites.
Low-growing palm trees add a tropical look to your Arizona yard. Selections include the Mexican fan palm (Brahea armata), which grows slowly to 15 feet tall. This evergreen grows in USDA zones 8 to 11 and tolerates drought, wind and sun. It blooms with aromatic white flowers, followed by edible black fruits. Another low palm, the Mediterranean fan palm (Chamaerops humilis), grows to 10 feet tall and is hardy in USDA zones 8 to 11. This slow-growing tree has blue- to dark-green leaves and thrives in hot, sunny and dry sites.
Other Desert Trees
For windy sites, plant an Arizona cypress (Cupressus arizonica). This native evergreen grows in USDA zones 7 to 9 and has blue- or gray-green foliage. Low varieties include the smooth Arizona cypress (Cupressus arizonica var. glabra), which reaches heights of 35 feet and has aromatic foliage. Another native tree, the Arizona rosewood (Vauquelinia californica) grows to 25 feet tall and creates shade with its linear evergreen foliage. Hardy in USDA zones 8 and 9, this white-flowering tree offers a nontoxic alternative to the toxic oleander (Nerium oleander) so often found in Arizona yards. Oleander grows in USDA zones 8 through 10.