Sun or partial shade. Mexican ash is weak-wooded, shallow-rooted, and not especially long lived. Despite these problems, it’s fast-growing, makes a nice shade, and can be useful in the right setting. It prefers deeper soils and riparian environments, so avoid thin rocky soils (and don’t plant too close to the house.) Mexican ash is often sold as “Arizona Ash” but in fact, the two species are different.
If structural integrity can be maintained by a good arborist, this ash can live fifty years or more. (Otherwise, it generally begins to lose the first big branches after twenty years, and quickly declines.) Only cut at a bud or branch; focus on minimizing the number of dead or damaged branches, and avoid “limbing it up” for a taller tree. Leave the upper 2/3 of the crown uncut to maintain a healthy specimen, and never remove more than the lowest third in a single 4-year pruning period.
