Does Palo Verde Mulch Have Thorns?

About Palo Verde Trees

• Mexican natives, sun-loving palo verde trees grow in U.S. Department of Agriculture plant hardiness zones 8 through 11. The small trees naturally form multiple trunks and produce ferny leaflets made up of many tiny oval leaves that allow sunlight to filter through the tree to allow planting underneath. The leaflets quickly drop, leaving the thready green center ribs of the leaflets. The bright green trunks are adapted to take over photosynthesis when leaves aren't present. In spring, the trees are covered with yellow flowers with red centers that attract bees and hummingbirds. Unfortunately, these trees then produce large seed-bearing pods that make palo verde a nuisance tree in some areas -- creating large, thorny thickets in vacant plots, roadsides and in wetlands.

Palo Verde Mulch Considerations

• Because palo verde is considered a "garbage" tree in some urban areas, its trimmings and even whole shredded trees may be found in the mulch produced by municipalities and commercial tree services. This landscape mulch, often offered free, includes roots, branches, leaves and twigs and usually thorns if the trees and shrubs involved in the clearing, cleanup or pruning project have them. It never hurts to ask the mulch provider if thorny brush is included in the mulch -- some municipalities either won't collect thorny yard waste or require that thorny brush be bundled separately -- though sturdy gloves and boots are still a good idea to avoid problems when applying any mulch. Arizona's Romeo Tree Service, which specializes in pruning palo verdes and other thorny trees, notes that its tree mulch is intended for tree beds and other landscape areas and should not be used where children or pets play because of thorns.

Mulch It Yourself

• Mulch from a specific tree variety is relatively rare, but when you're mulching a palo verde, its own clippings and seed pods can make the best mulch, according to Desert Harvesters, a nonprofit that promotes Sonoran Desert native plants. You can also control the number of thorns, or at least know where they are in your landscape. The organization suggests cutting prunings into pieces no larger than 4 inches long and arranging them, along with fallen seed pods, in rings 3 to 6 inches out from the base of the tree to avoid rot. Pieces too thick to cut with hand pruners or loppers can be chipped or shredded -- if you have access to the equipment -- or used as firewood. Avoid creating mats of mulch that could pose a tripping or fire hazard. You may also need to pull seedlings if the seeds in dried pods sprout.

Thornless Palo Verde Trees

• The exception to thorny mulch, of course, is when you grow or have access to the trimmings from a thornless palo verde variety. The cultivar "Desert Museum" (Parkinsonia x "Desert Museum") has the same green bark and rapid growth as the standard palo verde, but is completely thornless. A natural hybrid of three palo verde species, "Desert Museum" grows in USDA zones 6 through 9 and grows up to 20 feet tall and wide. The tree is semi-evergreen and -- like other palo verde trees -- drops leaves and branches to conserve water during dry periods. Unlike the standard species, "Desert Museum" -- named for the Sonoran Desert Museum in Arizona, which introduced the plant -- doesn't produce messy pods, so won't reseed.