Locust trees, including Black Locust (Robinia pseudoacacia) and Honey Locust (Gleditsia triacanthos), are hardy North American species found in diverse landscapes. This article examines their growth rate, influencing factors, and practical implications.
Understanding Locust Tree Growth
Trees are classified as fast-growing if they add 2 feet or more to their height annually. Locust trees consistently meet this, often exhibiting rapid growth. Black Locusts can grow 2 to 4 feet per year, especially when young, sometimes reaching 3 to 4 feet in a single season. Honey Locusts also demonstrate a fast growth rate. This allows them to quickly establish a substantial presence and develop a significant canopy faster than many other species.
Factors Influencing Growth Rate
Several environmental and biological factors shape the growth rate of locust trees. While both Black and Honey Locusts are fast-growing, specific Honey Locust cultivars like ‘Shademaster’ or ‘Sunburst’ are particularly noted for their rapid growth and adaptability.
Soil conditions significantly foster robust growth. Black Locusts adapt to various soil types, including poor, rocky, or alkaline soils, but thrive best in well-drained, moist, fertile conditions. Honey Locusts prefer well-drained, moist soil with a slightly acidic to neutral pH (6.0 to 8.0), tolerating diverse conditions like clay, sand, and saline soils. Adequate sunlight is also important; both species perform optimally in full sun, requiring at least six hours daily. Reduced light diminishes growth.
Water availability is important, especially for young trees, which need consistent watering to establish strong root systems. While mature locusts are drought-tolerant, drought impedes growth in new specimens. Climate and hardiness zones also affect growth; though hardy across USDA zones 3-9, extreme conditions impact vigor. Pests and diseases can slow growth. Black Locusts face locust borers and leaf miners, rarely leading to mortality. Honey Locusts can be affected by spider mites, gall midges, and webworms, but good growing conditions mitigate these issues.
Implications of Their Growth Rate
The rapid growth rate of locust trees has several practical implications. In landscaping, their fast development makes them suitable for quickly providing shade, privacy screens, or effective windbreaks. Honey Locust, with its fine leaves and open canopy, creates dappled shade, allowing other plants and grass to grow underneath.
Beyond ornamental uses, their quick growth contributes to their value in timber and wood production, especially for Black Locust, which yields durable wood. Both species are also used for erosion control and land reclamation due to their rapid establishment and extensive root systems that stabilize soil in disturbed or degraded areas.
However, vigorous growth necessitates specific maintenance. Rapid development can require increased pruning to maintain shape and manage weak branch structures. Vigorous root systems and suckering, particularly in Black Locust, need careful management to prevent unwanted spread. When planting, consider their mature size and fast growth rate to ensure adequate space and avoid conflicts with structures or utilities.