When Can You Trim a New Mesquite Tree?

Establishment

• During a mesquite's first three years, establishment of a strong, extensive root system is essential. This is particularly important in areas where winds from summer monsoons, typical of much of the Southwest, topple unstable trees. Growth-controlling plant hormones, called auxins, exist in the tips of branches and directly influence root growth. Pruning young mesquite reduces auxins, and inhibits the development of deep, healthy roots. Leaving branches intact during these formative years establishes the tree for the future. Plant mesquite in full sun with excellent drainage and room to grow. Depending on variety and water availability, mesquites can reach 30 feet or more in height and width.

Objectives

• Once mesquite reaches three years of age, roots should be established, and pruning is no longer detrimental. Always prune with specific objectives in mind. Mesquites are naturally multi-stemmed trees, and are stronger and more balanced when allowed to mature in their natural form. This makes trees less susceptible to wind damage and allows their graceful, arching habit to shade larger areas. It also reduces the need for constant pruning. Depending on species, mesquites can have thorns up to 2 inches long. When in a residential or public landscape, particularly near walkways, thorns and lower branches must be removed to eliminate the danger of injury to those passing by.

Pruning

• When pruning a young mesquite, start with the smallest branches at the bottom and work up. Leave large branches alone unless damaged, but remove all small branches and thorns at eye level or below. Hand pruners work best for this task. Wear protective sleeves and gloves, and sterilize your pruners prior to and between cuts to prevent the spread of disease. Leave branches growing outward and upward; prune those hanging down. Place pruners directly against the branch you want to keep. Put the branch you're cutting between the blades, at their base, not their tips. This creates a close, clean cut that heals quickly and redirects energy into remaining growth. Leaving a stub creates a potential hazard and an entry point for insects and disease.

Native vs. Non-natives

• Originating from several continents, numerous mesquite species and resulting hybrids can be found in American landscapes. Hardy in United States Department of Agriculture plant hardiness zone 7 and warmer, depending on variety, they all tolerate heat, low humidity and poor soils, and share the same pruning needs. But some important differences exist. Many non-natives grow quickly, are thornless and enjoy popularity. However, they tend to develop shallower root systems, have more surface-root problems and can topple in monsoon winds. Native mesquite trees rarely do. Non-natives require regular irrigation; natives survive on natural rainfall alone. Natives also attract more native birds and wildlife, that forage on their leaves and pods. Still fast-growing, natives grow slower than non-natives, but their greater stability results in longer life.