The Leyland Cypress is a fast-growing conifer hybrid widely valued for its ability to form dense privacy screens and hedges. Left unchecked, this vigorous plant can easily outgrow its intended space, sometimes reaching heights over sixty feet and a width of twenty feet. Pruning is necessary to manage this rapid growth, maintain the desired shape, and encourage the tight, dense foliage that makes it an effective screen. Consistent trimming prevents the plant from becoming oversized or sparse.
Timing and Necessary Tools
The ideal time for routine, light trimming is during the Leyland Cypress’s active growing season, generally spanning from late spring through late summer (April through August). This allows the plant enough time to heal and push out new growth before cold weather arrives. Heavier reduction cuts are best performed in the dormant season (late winter or very early spring). This timing reduces stress and minimizes sap loss.
A successful pruning session requires sharp, clean tools to make precise cuts that heal quickly and prevent disease. For routine shaping of new, soft growth, electric or gas-powered hedge shears or sharp manual bypass pruners are appropriate. Thicker, established branches require loppers or a pruning saw. Always wear safety gear, including thick gloves and eye protection.
Routine Shaping and Maintenance
Routine maintenance focuses on shearing the current season’s growth to promote a tight, multi-branched structure. The goal is to cut back the new, bright green tips of the foliage, stimulating the latent buds behind the cut to sprout. By making numerous shallow cuts, the plant is encouraged to produce more side branching, leading to a denser, more opaque hedge surface.
When shaping the sides of the cypress, it is beneficial to maintain a slight “A-shape,” or an inverted wedge, where the base of the hedge is slightly wider than the top. This contour allows sunlight to penetrate to the lower branches. If the top is wider, it shades the bottom foliage, causing those lower branches to thin out and eventually die. During a single routine maintenance session, remove no more than one-third of the current year’s new growth to avoid stressing the plant.
Controlling Height and Width
When a Leyland Cypress has exceeded its desired size, structural reduction cuts are necessary, involving the removal of older, thicker wood. Height reduction, often called “topping,” is achieved by cutting the central leader back to a lateral branch growing at the desired new height. This cut should be made just above a healthy side branch, which then takes over as the new terminal point. This helps conceal the cut and encourages a dense top.
Aggressive width reduction should be approached with caution, as these plants do not reliably regenerate from old, brown wood. To reduce width structurally, trace an overgrown branch back into the foliage and cut it off just above a smaller, healthy lateral branch growing inward. This technique directs the plant’s energy to the remaining inner growth. Structural cuts are more severe than routine shearing and should be performed less frequently.
Avoiding Common Pruning Errors
The most significant error when pruning a Leyland Cypress is cutting past the green needles and into the brown, interior wood of the branch. Unlike many deciduous shrubs, this conifer species does not possess the latent buds necessary to regenerate new growth from this older tissue. Cutting into the brown interior will create a permanent, dead, and unsightly brown patch that will not fill in.
Another common mistake is performing heavy pruning during the hottest part of the summer or too late in the fall. Pruning in hot conditions can stress the plant, and late-season pruning stimulates tender new growth that is highly susceptible to winter damage.
Additionally, avoid shearing the sides of a hedge so that the top is wider than the bottom. This incorrect shaping starves the lower limbs of sunlight, causing them to die.