For year-round beauty and sheer volume of spring color, few desert- adapted trees can rival the Blue Palo Verde, Cercidium floridum. The only others that possibly could, Sonoran and Foothill Palo Verdes, are botanical cousins. Blue-green bark, smooth on younger branches but becoming more grayish and fissured as trees mature, gives color to the graceful trunks and highly divided branches while providing a dark green backdrop for the intense yellow spring flower display. Flowers first appear in early spring and may persist into early summer. In mature, vigorous specimens, flowers literally cover the leaf canopy, creating masses of yellow in the landscape or dotting desert hillsides. When properly pruned, the trees reveal the color, texture and sculptural qualities of their trunks. The canopy is made up of finely-divided branches armed with small thorns, and compound leaves with 5 to 10 tiny leaflets.

Blue Palo Verde is native to the American southwest and northern Mexico (including Baja California) and is widely distributed across this range from sea level to four thousand feet. This species is highly adapted to desert conditions, tolerating high summer temperatures, and is cold hardy to 10 to 15 degrees. It is found naturally along desert washes and on hillsides where soils are reasonably developed and where some summer soil moisture is available.

In native settings Blue Palo Verdes grow as large shrubs, 25 to 35' tall and as wide, with branches that extend all the way to the ground. This mounding grow habit provides resistance to winds, reduces evaporation of moisture from the soil directly beneath the tree and inhibits the growth of other plants that may ultimately compete for the limited amount of seasonal rain.

PLACEMENT: When placing Blue Palo Verdes in the landscape, take into account the mature size of the tree, which can exceed 30' x 30', and the moderately dense shade they produce. Summer shade may limit the growth and flowering of some under-story plantings and inhibit the growth of some turf grasses. Palo Verdes will tolerate a range of soil types and sun exposures. Best growth is achieved when trees are planted in full sun and well-draining soils. Small thorns are present. Trees can be pruned up to produce a canopy over a seating area or allowed to grow to the ground to provide a dense, effective screen, windbreak, perimeter barrier or to create wildlife habitat.

TURF AND NON-TURF PLANTING: Planting Blue Palo Verdes in lawn areas can create challenges, particularly if lawns are over-seeded with winter rye grass. Fertilization and irrigation in the winter months (needed by winter rye grass) when tree growth is slow, can promote the development of root diseases that can seriously damage or kill trees. These irrigations and fertilizations promote late-season, succulent branch growth that is more susceptible to freeze damage. Lawn planting also raises the risk of trunk injury from mowing and trimming equipment. Blue Palo Verdes have virtually no bark protecting the trunk tissues from injury, making them easily damaged by power mowers and string trimmers. This is not to suggest that it is impossible to maintain Blue Palo Verde successfully in lawns, but rather that these trees will require special care and management to survive in these settings. Planting in non-turf areas offers the possibility of naturalizing trees once they are established and have reached the desired size and structure. Weaning desert adapted trees off regular irrigation helps control tree size, manage growth and limit pruning without compromising tree vigor or flowering.

PESTS AND DISEASES: Spider Mites can attack Blue Palo Verde, causing "Witches’-broom," the production dense clusters of small branches arising along the branch or at the tip. Mistletoe can also infest these trees. To a limited extent witches’-broom and Mistletoe can be controlled with pruning. Both are largely cosmetic problems and, while they can diminish overall vigor of trees, will not, by themselves, kill the tree. The Palo Verde Root Borer is the only lethal insect pest but it tends to attack only stressed or declining trees. The best protection from borers is to keep trees vigorous and generally healthy. Root rot can develop in highly saturated, over-irrigated soil. Trees are particularly vulnerable immediately following transplanting. This disease is easily avoided by proper irrigation management.

LANDSCAPE USES: The natural form of Blue Palo Verde, like most desert species, is multiple trunked or a short, 1 to 2 foot, single trunk with multiple trunks originating from that point. The multiple trunked and low-breaking types are the most commonly used in landscape designs. In nursery production tall, upright "standard trunk" specimens can be produced but much of the tree’s natural beauty and desert character is compromised in the process.

With its flower displays, blue-green color and unique texture, Blue Palo Verde is a versatile, highly adaptive landscape tree. Its uses include: as single large specimens or small groupings as a landscape focal point; at project entries; near monuments or signs; or at tee boxes, greens and along fairways in golf courses. Its desert form and character make it ideal as a transition tree between landscaped areas and undisturbed desert or as a theme tree in large landscape designs. They are also use in streetscape and perimeter planting in commercial, residential and municipal landscapes.