Mesquite trees belong to the genus Prosopis, a group of thorny shrubs and trees in the legume family Fabaceae. These species are native across a wide range, primarily the Southwestern United States, Mexico, and South America. Known for their resilience, mesquites are highly adaptable to arid and semi-arid regions. The rate at which a mesquite tree grows is not fixed; instead, it is highly dependent on local environmental conditions and the specific species or variety.
Understanding the Typical Growth Rate
Mesquite trees are generally classified as having a medium growth rate, increasing in height about 12 to 24 inches per year in optimal settings. Young plants can grow faster, with seedlings capable of reaching 3 feet during their first year when provided with irrigation and heat. The initial juvenile stage lasts two to three years and is marked by rapid root development, allowing the plant to reach 5 to 6 feet in height quickly.
Single-stemmed trees, which occur where water is consistently available, can eventually reach mature heights between 20 and 40 feet. Some specimens may reach 50 feet under ideal conditions. However, in harsh, water-limited environments, a tree’s age does not necessarily correlate with its size, demonstrating extreme variability in growth.
Environmental Factors Influencing Speed
Water availability is the most influential factor dictating the growth rate of a mesquite tree. When water is abundant, such as through irrigation, the tree adopts an upright, single-stemmed habit and achieves its maximum vertical growth rate. Conversely, in arid environments, the plant slows its growth to conserve moisture and presents as a short, multi-stemmed shrub. Mesquite uses two to three times more water than surrounding herbaceous vegetation.
Soil conditions also significantly impact the tree’s potential for height and speed. Deep, well-drained soils allow the taproot to establish quickly and penetrate to maximum depths, supporting a taller, more vigorous tree. Shallow soils restrict this downward growth, forcing the tree to develop an extensive lateral root system that limits vertical development.
Temperature plays a role, especially during the establishment phase of a seedling. Mesquite requires a minimum soil temperature of at least 77 degrees Fahrenheit to establish, with optimal growth occurring between 80 and 90 degrees Fahrenheit. Maximum shoot growth is achieved through a combination of optimal soil temperature and warm aerial conditions.
Unique Mesquite Adaptation Strategies
Mesquite’s success in harsh environments is attributable to its sophisticated root architecture. The tree is a facultative phreatophyte, meaning it can extract moisture from a large volume of soil. Its taproot commonly reaches depths of 40 feet when subsurface water is available, with some observations recording depths up to 190 feet. This deep penetration allows the mesquite to maintain metabolic functions during extreme drought conditions.
The plant also develops an extensive network of lateral roots that can spread up to 60 feet from the trunk to capture surface moisture. This dual root strategy enables the tree to be highly resilient, allowing it to shed its leaves and slow growth during severe dry spells without dying. Furthermore, as a member of the legume family, the mesquite engages in nitrogen fixation. This process converts atmospheric nitrogen into a usable form, effectively fertilizing itself and enriching the surrounding soil.
Managing Growth and Spread
Managing mesquite often involves control, especially in rangelands where it can aggressively spread and crowd out grasses. For landscape specimens, directing growth involves proper pruning, which is best done in the winter or late spring to shape the canopy. A common practice is to remove no more than 25% of the canopy at one time to prevent excessive stress.
Controlling unwanted mesquite requires targeting the plant’s robust root system and basal buds. Herbicide application is most effective when the tree is actively moving carbohydrates down to the roots, occurring 45 to 90 days after spring bud break. A foliar spray is generally utilized for bushy, multi-stemmed plants. A basal bark treatment is best suited for younger trees with smooth trunks less than four inches in diameter.