This relative of the Palo Verde tree is really not recommended for our USDA Zone 9b, but it is very popular in the Phoenix area for areas that take a smaller tree. It does well in full and reflected sun and takes little to no supplemental water once established. I thought this was the perfect location for this Palo Brea when I planted it two years ago because it has a southwest exposure and a lot of reflected sun from the adjacent driveway to my husband's shop. It will eventually provide filtered shade for a large glass block window and a rose bed.
The Palo Brea can reach 40 ft. high, but that is rare in this climate. More than likely it will reach a maximum of 25 ft. with a 20 ft. spread over many years. The tree has the typical Cercidium green trunk, with arching branches. The downside of this tree is that the branches are covered with thorns, and more than once, I've ducked under the branches while taking a shortcut to the shop and suffered the consequences with numerous scratches. Not only does it scratch, the branches seem grab you and it's hard to extricate yourself without additional scratches! I'm slowly raising the canopy by pruning the lower branches. Since end pruning is not good, the long arching branches pose a danger until the tree is quite a bit taller.
I've always loved the shape of this Cercidium species. The mature trees are especially attractive in spring when bright yellow flowers cover each branch from tip to base, which serves to emphasize the arching growth habit.Unlike the other trees in my landscape that started out as 24-inch boxed trees, this one was in a 15-gallon container, so it is still small, even after two years. I did not need to stake it at all, and it has withstood many summer monsoon windstorms. One of the reasons our region is not considered the optimum climate for this tree is that it is less hardy than the other Palo Verde species, and we occasionally have frost. It is hardy to 22°F., a temperature we very rarely see, even in our coldest winters. This tree was just getting established when we had the freak freeze a couple of years ago where our temperature got down to 18°F. There was only some very minor frost burn to the newer leaves, so I'm not worried about it at all.