The genus Cornus, which includes the popular flowering dogwood (Cornus florida) and Kousa dogwood (Cornus kousa), features highly sought after ornamental trees. Dogwoods are known for their distinctive tiered structure and beautiful spring blooms. Because these trees are long-lived and develop a specific mature shape, determining the correct planting distance is important for ensuring their long-term health and maximizing their aesthetic appeal.
Standard Spacing Requirements
The appropriate distance between dogwood trees is determined by the full, mature width of the specific cultivar being planted. For the native flowering dogwood, Cornus florida, which matures to a width between 15 and 30 feet, a standard spacing of 20 to 30 feet is recommended to prevent canopy overlap. The Kousa dogwood, Cornus kousa, displays a more upright growth habit, allowing for spacing of 15 to 25 feet between trunks.
Spacing should always be measured from the center of one tree trunk to the center of the next. A practical rule is to plant the trees at a distance equal to or slightly greater than the expected mature canopy width. This ensures the full spread of the branches is accommodated, preventing overcrowding issues later.
Adjusting Spacing Based on Planting Goal
While the mature width provides the standard distance, the specific landscape goal modifies the final spacing decision. When the intent is to highlight the tree’s natural form, known as specimen planting, the maximum distance is preferred. Placing a dogwood 25 feet or more from other plants allows the canopy to fully develop its characteristic horizontal, tiered branching structure, showcasing the tree as a focal point.
Conversely, if the goal is to create a dense grouping or a continuous border, the trees can be planted slightly closer together. Reducing the distance to approximately 12 to 15 feet encourages the individual canopies to eventually merge, creating a solid mass of foliage and blooms. This intentional crowding sacrifices the distinct, individual form for a more unified visual barrier, but spacing must still support the health of each tree.
Consequences of Incorrect Spacing
Planting dogwood trees too close together creates a high-stress environment that compromises the tree’s health and structure. Overcrowding immediately reduces air circulation around the foliage, contributing to fungal diseases common in dogwoods. Fungal issues like powdery mildew and various leaf spots thrive in damp, stagnant air conditions created when canopies are tightly packed together.
Insufficient spacing leads to competition between trees for resources. The shallow, fibrous root systems of dogwoods will compete for water and nutrients in the soil. This root-zone competition results in stunted growth, reduced vigor, and a diminished capacity to produce blooms.
The aesthetic appearance of an overcrowded dogwood is also negatively affected. Instead of developing the naturally broad, spreading crown and horizontal branch tiers, the trees are forced to grow tall and spindly. They reach upward, sacrificing their graceful, ornamental shape for a narrow, columnar form.