How a Hedge Trimmer Cuts

Hedge trimmers cut by catching stems between rows of teeth and shearing them as the blade edges pass one another. Depending on the design, both blades may move back and forth, or one may move against a stationary blade. The tool’s stated cutting capacity—not just its motor power—indicates how thick a branch it is meant to cut.

How the blades shear stems

Each blade has a row of teeth with cutting edges. As the blades slide past one another, the teeth trap a stem and the opposing edges shear through it, much like scissors. The reciprocating motion repeats rapidly while the trimmer is running.

The teeth are designed to cut small branches and leafy growth. A stem that is too thick may sit between the teeth without being cut, or make the trimmer slow down or stall. Don’t force it: use hand pruners or loppers for thicker branches.

What tooth spacing and cutting capacity mean

Tooth spacing is the distance between adjacent teeth. Wider spacing can accommodate larger stems, but it does not guarantee that the trimmer can cut every stem that fits between the teeth. The blade shape, motor, and overall design also matter.

Check the manufacturer’s stated maximum cutting capacity and follow its guidance. Hedge growth that is very hard, dry, or tangled may be harder to cut than fresh, flexible growth of a similar thickness.

Why sharp, clean blades matter

Clean, sharp blades pass through stems more effectively. Sap and debris can make blades drag or stick, while dull or damaged edges can leave ragged cuts and strain the tool. Clean and lubricate the blade as directed in the manual, and inspect it for bent or chipped teeth before use.

Before touching or cleaning the blade, switch the trimmer off and disconnect its power source. Remove the battery or unplug the tool; for a gas model, follow the manufacturer’s instructions to make it safe. Wear gloves when handling the blade.

When a hedge trimmer is the wrong tool

A hedge trimmer is intended for shaping and maintaining hedges, not for cutting large branches or making precision pruning cuts. If stems exceed the stated cutting capacity, use an appropriately sized hand tool or consult a qualified professional for large or hard-to-reach growth.

If the trimmer struggles with growth well within its rated capacity, stop and check for a dirty or damaged blade, a jam, or an incorrectly fitted part. Use only compatible replacement blades. If the blade is bent, badly chipped, or cannot be made to cut properly after the maintenance described in the manual, replace it or have the tool serviced.