A tall hedge is a living screen exceeding ten feet in height, planted primarily for year-round privacy and boundary demarcation. Achieving a tall, dense hedge rapidly requires selecting a species with a high inherent growth rate and actively managing its environment and growth habit. The goal is to install a solid, green wall quickly, which necessitates both genetic potential and optimal care. Understanding the biological potential of the fastest-growing species, coupled with providing ideal conditions, is the most direct path to rapid installation.
The Fastest Growing Tall Hedge Species
The fastest-growing tall hedges are specialized evergreen conifers known for significant annual vertical growth. The Leyland Cypress (x Cuprocyparis leylandii) is recognized for its speed, capable of adding three to five feet of height per year under optimal conditions. This hybrid conifer can reach 60 to 100 feet, forming a dense, pyramidal shape ideal for large-scale screening. It is a highly adaptable species, thriving across a wide range of climates.
Another top contender is the Thuja ‘Green Giant’ (Thuja plicata x standishii), a hybrid arborvitae celebrated for its excellent disease resistance and robust growth. This species also routinely achieves growth rates of three to five feet annually once established. The ‘Green Giant’ typically grows 40 to 60 feet tall and maintains a dense, conical form with foliage that remains lush to the ground. Its natural shape and hardiness make it a favored alternative to the Leyland Cypress.
While other plants like certain fast-growing privets (Ligustrum spp.) are quick, with a rate of two to three feet per year, they do not match the vertical speed of the two conifers. Selecting one of these two species provides the maximum genetic head start for a rapid privacy solution.
Environmental Conditions That Maximize Growth Rate
Optimal external conditions are required for the fastest-growing plants to achieve their maximum potential of three to five feet of vertical growth annually. Sunlight is a primary driver, and both Leyland Cypress and Thuja ‘Green Giant’ need a minimum of six hours of direct, unfiltered sunlight daily. Planting in full sun ensures the highest rate of photosynthesis, which fuels vertical growth. While both species tolerate partial shade, their growth rate will be significantly reduced.
The most important soil condition for these conifers is excellent drainage, as they are highly susceptible to root rot in soggy environments. Although they are adaptable to various soil compositions, the site must not retain standing water. A simple drainage test involves digging a hole twelve inches deep and filling it with water. If the water remains for more than two hours after the second filling, the site’s drainage must be improved.
Consistent water availability during the establishment phase is crucial to sustain the rapid growth rate. Newly planted hedges require the soil to be kept consistently moist, not saturated, for the first few months. A general guideline is to provide approximately one inch of water per week, particularly during the first two to three years as the root system develops. Proper watering early on is necessary to prevent the growth rate from stalling due to transplant stress.
Essential Techniques for Establishing a Dense Privacy Screen
Proper planting technique is essential to ensure that rapid vertical growth translates into a dense, solid visual barrier. The initial size of the plant matters, as smaller, container-grown stock (three to five feet tall) often overcomes transplant shock faster than very large specimens. When planting, the hole should be dug two to three times wider than the root ball, but only as deep, ensuring the root flare is level with or slightly above the surrounding soil grade. The soil used to backfill the hole should be lightly tamped to eliminate air pockets. Apply a two to three-inch layer of organic mulch, keeping it several inches away from the trunk.
Spacing is a critical factor in balancing growth speed with ultimate density. For an immediate screen, Thuja ‘Green Giant’ should be planted approximately five to six feet apart, while Leyland Cypress needs six to eight feet of separation to allow for adequate air circulation. Planting too far apart delays the formation of a solid wall, while planting too close together restricts airflow and light, increasing the risk of disease. Achieving density also depends on strategic pruning, which must begin early in the plant’s life.
To encourage lateral growth and density, a technique called “tipping” or light shearing should be performed on the side branches during the growing season in the first few years. This involves cutting back the side shoots by up to one-third of their length to stimulate branching. The vertical leader, or main central shoot, should be left uncut until the hedge reaches the desired mature height, which ensures maximum vertical speed is maintained. Once the desired final height is reached, the leader can be cut back slightly to encourage the top of the hedge to thicken into a dense cap.