The decision of how far apart to plant evergreen trees is the single most important factor for their long-term health and aesthetic success. Incorrect spacing leads to stunted growth, disease vulnerability, and eventual loss of lower branches as the trees compete for light and nutrients. Correct spacing ensures they mature into healthy, full specimens or a dense, uniform screen.
The Foundation: Understanding Mature Dimensions
Proper spacing begins not with the size of the sapling you purchase, but with the tree’s anticipated mature width. Every evergreen species and cultivar has a genetically determined maximum width reached over many years. For instance, a columnar variety like ‘Emerald Green’ Arborvitae may mature to a width of 4 feet, while a wide-spreading Austrian Pine can reach 25 to 30 feet wide.
Ignoring the mature width is a common error that results in overcrowding a decade or two later. Information regarding a tree’s mature width is found on nursery tags, in gardening books, or through online horticultural databases. This measurement is the foundation of all spacing calculations, as it dictates the minimum room an individual tree needs to fully develop its canopy and root system.
Trees planted too closely together will never achieve their natural, full shape because their lower branches will be shaded out and die due to competition for light. This loss of lower foliage creates an unsightly “skirt” look, defeating the purpose of planting a dense evergreen screen. Using the mature width ensures that each tree receives adequate sunlight and air circulation to thrive for its entire lifespan.
Calculating Distance Based on Landscape Goal
The exact planting distance is a function of the tree’s mature width combined with the specific goal for the planting. Different landscape objectives require different levels of canopy overlap, resulting in varied spacing formulas.
Privacy Screens and Hedges
For creating a dense, solid visual barrier, evergreen trees are intentionally planted closer together to ensure their canopies grow into one another. The rule for a privacy screen is to plant trees at a distance equal to one-half to two-thirds of their mature width. For example, if a tree is expected to reach a mature width of 10 feet, planting them 5 to 7 feet apart will cause the branches to interlock and form a seamless wall of foliage.
This close spacing creates immediate density but requires monitoring to ensure the trees do not experience undue stress from resource competition. For fast-growing, narrow cultivars like ‘Green Giant’ Arborvitae (which can mature to 15 feet wide), spacing them 5 to 8 feet apart is common to achieve a solid screen. Planting too far apart leaves visible gaps, while planting too close can lead to premature decline.
Specimen Trees
When the goal is to showcase an evergreen as a standalone feature, maximizing its individual growth and aesthetic display is necessary. For a specimen tree, the proper planting distance is its full mature width plus an additional 5 to 10 feet of clearance from nearby objects or other trees. This space ensures that the tree’s lower branches are exposed to sunlight, allowing the canopy to fully develop into its natural, conical or pyramidal form.
A spruce that matures to a 20-foot width should be planted at least 25 to 30 feet away from any other large tree or structure. This allows for ample air circulation, reducing the risk of fungal diseases, and provides the root system with an undisturbed zone for nutrient and water uptake. This strategy prioritizes the long-term health and full expression of the tree’s genetic potential.
Windbreaks and Shelterbelts
Windbreaks are designed to slow wind across a large area, often involving multiple rows of trees in a staggered pattern. Spacing within a single row for a dense windbreak ranges from 6 to 12 feet for smaller species and 8 to 18 feet for larger ones. The trees in the row are planted close enough to create a dense wall but far enough apart to minimize resource competition over time.
For multi-row windbreaks, the distance between the rows should be significantly wider, often 12 to 20 feet apart, to allow for maintenance and reduce competition for soil moisture. The ideal design involves staggering the trees in adjacent rows so that the second row fills the gaps left by the first row, creating a more effective barrier against the wind.
Environmental Factors Affecting Spacing
While mature width provides the baseline, site-specific environmental conditions may necessitate minor adjustments to the calculated distance. These factors influence how vigorously an evergreen can grow.
In areas with poor soil quality (such as heavy clay or very sandy, nutrient-poor ground), increasing the calculated spacing slightly can be beneficial. Giving the trees a few extra feet reduces the competition for limited soil nutrients and available water. Conversely, in highly fertile soil with consistent irrigation, trees may tolerate the closer end of the recommended spacing range.
Planting on a slope requires careful consideration of drainage patterns and soil stability. On steep banks, slightly closer planting may help stabilize the soil with a network of roots. However, poor drainage at the base of a slope may necessitate wider spacing to prevent root rot.
Any evergreen planted near a house, foundation, or underground utility line requires extra clearance, often 10 to 20 feet away. This distance is necessary to prevent future structural damage from root expansion.