Arborvitae (Thuja) is a highly favored evergreen for creating dense, year-round visual barriers because of its rapid growth and naturally columnar shape. Successfully establishing a solid privacy screen, however, depends entirely on selecting the correct planting distance for the specific variety. Planting too far apart leaves gaps for years, while planting too close compromises the long-term health and density of the hedge. This guide provides the specific, actionable planting distances and techniques required to achieve a successful and solid green wall.
Calculating Spacing for Immediate Privacy
A common formula for immediate screening is to plant arborvitae at a distance equal to half of the plant’s projected mature spread. If a particular cultivar is expected to reach a mature width of eight feet, planting centers should be set at four-foot intervals. This tighter spacing accelerates the formation of a continuous visual barrier.
Planting too densely can restrict air circulation and light penetration once the trees mature, which increases the risk of fungal diseases and pest issues like bagworms. For homeowners with more space, a staggered, double-row configuration offers the fastest and densest coverage while promoting better air flow between plants.
In a staggered arrangement, the second row is offset diagonally into the gaps of the first row, maximizing the visual blockage. This configuration requires purchasing more trees but provides an immediate, robust screen that is healthier than an overly crowded single row.
Matching Spacing to Arborvitae Cultivar
Spacing must be determined by the specific cultivar’s mature size. The popular ‘Green Giant’ (Thuja plicata x standishii) grows exceptionally wide, sometimes reaching 12 to 20 feet in spread at full maturity. For a solid screen, ‘Green Giant’ requires spacing, generally planted five to eight feet apart on center to ensure long-term health and access to light.
In contrast, the ‘Emerald Green’ (Thuja occidentalis ‘Smaragd’) is a narrow, columnar cultivar that typically reaches a mature width of only three to four feet. This slender habit allows for tighter spacing, with plants set three to four feet apart on center to quickly form a dense, formal hedge. Choosing a cultivar that naturally fits the space prevents the need for constant maintenance pruning.
The ‘Nigra’ or Dark Green Arborvitae (Thuja occidentalis ‘Nigra’) represents a mid-range option, maturing to a width of five to ten feet, depending on conditions. This variety should be spaced four to six feet apart on center, balancing dense coverage with the need for adequate room to develop.
Soil Preparation and Planting Technique
Before planting any arborvitae, evaluating the soil’s drainage capacity is necessary, since these plants are highly susceptible to root rot in soggy conditions. A simple percolation test can be performed by digging a twelve-inch deep hole, filling it with water, and timing how long the water takes to drain completely. Soil that drains at a rate of one inch per hour is considered well-drained and suitable for planting.
The planting hole should be two to three times the width of the root ball. However, the depth of the hole must be exactly the same as the root ball to ensure the root flare—where the trunk begins to widen—sits level with or slightly above the finished soil grade. Planting too deeply suffocates the roots and leads to decline.
If the root ball is bound tightly, it is necessary to score or lightly shave the outer surface with a knife or spade. This action cuts the circling roots, encouraging new feeder roots to grow outward into the native soil rather than continuing to girdle the plant.
Care Requirements for Mature Privacy Screens
After planting, newly planted arborvitae benefit most from deep, infrequent soakings that saturate the soil to a depth of at least six to eight inches, rather than shallow, daily sprinkles. This practice encourages roots to grow downward, making the plant more tolerant of dry spells once established.
It is also important to maintain a sufficient watering schedule through the late fall and early winter months. Evergreens continue to lose moisture from their foliage year-round, and winter desiccation is a leading cause of browning. A high-nitrogen, slow-release fertilizer, such as one with an NPK ratio around 10-5-5, should be applied in early spring to established trees to support the growth of dense, green foliage.
To ensure the screen remains dense from top to bottom, light, annual pruning is recommended to encourage lateral branching. This technique, often called “tipping” or light shearing, involves cutting only the tips of the new growth early in the season. Pruning stimulates the plant to produce more side shoots.