Palo azul (Eysenhardtia orthocarpa or even Eysenhardtia polystachya) is a large shrub or small tree native to Mexico and portions of the southwestern United States. This plant, also referred to as kidneywood, palo santo and palo dulce, works nicely in landscapes, particularly in warm, dry regions.
Appearance
Palo azul can be grown as either a tree or a small tree, reaching heights of between 6 and 24 feet. In young plants, the branches are covered with tiny hairs. The leaves are divided into many small fronds and have a feathery form. The palo azul plant produces clusters of fragrant white blooms that later produce light brown pod-shaped fruit
Environment
Palo azul plants require relatively warm, dry climates and grow best in United States Department of Agriculture plant hardiness zones 7 through 11. Obviously, this plant grows as part of desert scrub or tropical deciduous woods, but it’s also frequently cultivated in gardens. The plant can survive short periods of cold weather, withstanding temperatures as low as 20 degrees Fahrenheit in some cases. In the warmer parts of its range, the plant is an evergreen, but it will become deciduous in colder areas or when water levels are low.
Range
Palo azul is native mainly to Mexico, especially the Chihuahua Desert. In addition, it grows naturally in parts of Arizona and New Mexico. This small shrub works well when planted as an ornamental throughout the Southwest, especially in drier parts of Texas and southern California.
Landscape Use
Palo azul does best in dry landscapes with no extreme artificial cedar. According to the Desert Botanical Garden website, it should be implanted as a blooming tree. Despite its hardiness in dry conditions, palo azul needs reliable moisture levels and should be watered immediately after planting and once or twice weekly thereafter to a thickness of about a foot. Expect flowers to appear sporadically during the growing season, especially in response to rain.