Design

Professional pruning shears often have replaceable blades.

There are three different blade designs for pruning shears: anvil, bypass and parrot-beak.

Anvil pruners have only one blade, which closes onto a flat surface; unlike bypass blades it can be sharpened from both sides and remains reliable when slightly blunt. Anvil pruners are useful for cutting thick branches; one can bite into the stem from one direction, swing the handle around and bite further through narrowed wood from another direction. The anvil is made of a material softer than the blade, so that the blade is not damaged when it meets the anvil. Suitable materials for the anvil are plastic, aluminum, zinc, brass, or bronze alloys. The blades are made from hardened carbon or chromium steels.

Bypass pruners usually work exactly like a pair of scissors, with two blades "passing by" each other to make the cut. At least one of the blades will be curved: a convex upper blade with either a concave or straight lower one. Some bypass designs have only one blade, the lower jaw being broad (like an anvil) but passing the upper jaw. The ratchet pruner, which can handle stems thicker than two centimeters, fits in this category. Because they make a clean cut without crushing, bypass pruners are preferable for pruning live wood. 

Parrot-beak pruners consist of two concave passing blades, which trap the stem between them to make the cut. These are suitable only for narrower stem