Pollarding is a specific and cyclical tree management technique that involves the severe pruning of a tree’s upper branches. This method is used to control the height and lateral spread of the tree. When done correctly, pollarding encourages a dense head of new foliage to grow from the cut points, maintaining the tree at a predetermined size.
Defining Pollarding: Purpose and Historical Context
Pollarding is an ancient method of pruning that manages the size and structure of trees, functioning as a continuous and managed process. Historically, the practice was widespread throughout Europe, with records of its use dating back to the Roman Empire around the first century BCE. The original purposes were largely utilitarian, focused on harvesting resources.
Farmers would pollard trees to provide a sustainable source of firewood, fencing materials, and even fodder, or “pollard hay,” for livestock. Cutting the branches above the height of grazing animals, typically seven to eight feet, allowed the woody material to grow back without being eaten. In modern urban environments, the purpose has shifted to size control and aesthetic management. Pollarding is now primarily used to keep trees at a manageable height in confined spaces, prevent interference with utility lines or buildings, and reduce the risk of large, heavy limbs failing. This technique creates a permanent structure, often referred to as a “knuckle” or “bolling,” from which all subsequent new growth emerges.
Proper Execution: Initial Cuts and Ongoing Maintenance
Successful pollarding depends upon establishing the permanent framework and adhering to a continuous maintenance cycle. The process begins with the initial cut, where the main limbs of a young tree are headed back to a set height, typically on the main trunk or a few lateral branches. These initial cuts, which should be made just above a bud or lateral branch, create the foundational “pollard head.”
The best time for this initial cut and all subsequent maintenance is during the tree’s dormant season, generally late winter or early spring before new leaves emerge. This timing minimizes stress on the tree and reduces the risk of fungal entry into the large wounds. Once the framework is established, the tree responds by producing vigorous new growth, known as epicormic shoots, from the cut points.
Ongoing maintenance requires cutting back this vigorous new growth to the same pollard head every one to three years, depending on the species. The cut must be made precisely just above the existing knuckle. Consistent adherence to this cycle prevents the new epicormic shoots from growing too large, which would make the subsequent cut a major, stressful wound rather than a routine trim.
The Critical Difference: Pollarding vs. Tree Topping
The managed, cyclical practice of pollarding is frequently confused with the harmful practice known as tree topping. Topping is an indiscriminate cutting method that removes the upper crown of a tree to an arbitrary height, often cutting back to weak lateral branches or leaving large, unmanaged stubs. This aggressive, unmanaged removal of the canopy severely stresses the tree, forcing it to expend massive amounts of stored energy to survive.
Topping creates extensive, non-compartmentalized wounds that serve as easy entry points for decay, pests, and disease. The new growth that sprouts after topping, often referred to as “watersprouts,” is weakly attached to the remaining stub and is structurally unsound, leading to a high risk of future branch failure. In contrast, pollarding establishes a permanent, managed knuckle structure that is intentionally designed to support the predictable, dense regrowth. The repeated, precise cuts in pollarding encourage the tree’s natural defense mechanisms to compartmentalize the wounds.
Selecting Suitable Tree Species
Pollarding is a technique that can only be successfully applied to certain species that possess a strong ability to regenerate new growth from dormant buds after a severe cut. Deciduous trees that are vigorous growers are generally the best candidates for this treatment. Highly suitable species that respond well to pollarding include the London Plane, various species of Linden, Willow, and certain Maples and Oaks.
The success of the technique depends on the tree’s ability to compartmentalize the wounds effectively and quickly produce strong epicormic growth. Trees that should not be pollarded include most conifers, trees that bleed copious amounts of sap, or those that lack the necessary regenerative capacity. It is also important that the pollarding process begins when the tree is young, as attempting to pollard a mature tree that has never been cut before can be highly detrimental and potentially fatal to its health.