Pruning shears are fundamental tools in gardening and horticulture, designed for trimming and shaping plants. Selecting the correct type of shear is crucial, as the tool’s action directly impacts the health and recovery of the plant material being cut. While all hand pruners cut stems and small branches, their specific cutting mechanisms determine which tasks they perform best. Understanding these differences allows a gardener to choose the right instrument for a given job, promoting vigorous growth and preventing plant damage.
Defining the Structure and Action
Bypass pruning shears operate using a mechanism similar to a pair of scissors, where two curved blades pass closely by one another to make a cut. This design involves a sharp cutting blade that glides past a thicker, often unsharpened, lower blade known as the hook or counter blade. The pivot point, where the blades meet, provides the necessary leverage for the cutting action.
The primary function of the hook blade is to stabilize the stem while the cutting blade slices through the material. This shearing motion allows for a clean and precise severing of the plant tissue without crushing or tearing. A spring mechanism pushes the handles apart after each cut, and a locking mechanism keeps the blades safely closed when not in use. The clean cut minimizes the wound surface area and facilitates faster plant healing.
Ideal Applications for Bypass Shears
The clean, slicing action of bypass shears makes them the preferred tool for working with living plant material. They are specifically designed for pruning live, green wood, soft stems, flowering plants, and shrubs. Because the blades pass by each other, they create a smooth incision that does not damage the delicate internal structures of the stem.
This precise cut is important for maintaining plant health, as it minimizes the area where pathogens or pests can enter, reducing the risk of disease and infection. Gardeners use them for tasks like deadheading flowers, shaping young shrubs, and pruning rose canes, where the goal is quick healing and new growth. Bypass pruners are generally best suited for stems up to about three-quarters of an inch (20-25 millimeters) in diameter.
Bypass Versus Anvil Pruners
Bypass shears are often contrasted with anvil pruners, which employ a distinctly different cutting mechanism. Anvil pruners feature a single, straight cutting blade that closes down onto a flat, fixed base, called the anvil. This action is comparable to using a knife against a cutting board, where the material is compressed and chopped.
The forceful compression of an anvil pruner results in a crushing action, which severely damages the soft tissue of a living stem. This makes anvil pruners less suitable for live plants, as the resulting wound takes longer to heal and can lead to dieback. Anvil pruners are instead best applied to pruning dead, tough, or dried-out wood where crushing the material is not a concern.