How to Use an Edge Trimmer? | Clean Lawn Borders Guide

Knowing how to use an edge trimmer properly separates a crisp lawn border from a ragged, hacked-up one. The core method is simple: convert the head to edging position, keep the line lightly touching the edge, and walk at a steady, unhurried pace. Whether you own a string trimmer with an edging mode or a dedicated lawn edger, the same principles apply—and a few common mistakes ruin more edges than bad tools ever do.

First, Set the Head for Edging

The single most important step is getting the cutting head into the right position. A trimmer cuts horizontally; an edger cuts vertically against the turf border. Most combo tools switch between these with a twist.

On a Flymo trimmer/edger, the process is specific: depress the locking button and twist the head anti-clockwise until the arrow lines up with EDGE. You’ll hear an audible click confirming it’s locked, then release the button. To return to trimming mode later, depress the locking button and twist the head clockwise until the arrow points at TRIM, again waiting for the click. Some other brands, like certain Home Depot-sold models, simply require pushing down and rotating the head 180 degrees. Check your manual’s diagram, but the locking click is universal—if you don’t hear it, the head isn’t secure.

Grip, Stance, and the Right Cutting Angle

Hold the trimmer with both hands and keep the unit at or below waist level. The cutting head must sit vertical—perpendicular to the ground—not tilted broadly across the turf. That 90-degree angle is what produces a clean, defined channel along the walkway or flower bed.

Set the trimmer on its roller or skid plate if it has one; this keeps the head stable at a consistent height as you move. Start the trimmer before you approach the grass, and always let the line reach full speed before it contacts anything. When cutting, use the tip of the nylon line at an angle and take small cuts rather than forcing the line deep into thick material. For general trimming (not edging), one operator’s manual recommends a cutting angle of 5 to 10 degrees—but edging is different, and vertical is the goal.

Walk Slowly, Work With the Rotation

Movement direction matters more than most people think. Work along the edge so debris is thrown away from you—this often means moving right to left, or the opposite direction of the line’s spin. Slow and steady wins here; rushing is how uneven edges and chunks of turf torn out happen.

Before you start, clear the area of stones, toys, and ornaments. Flying debris is the biggest hazard, and heavy clothing plus eye protection aren’t optional. Don’t cut damp or wet grass, and don’t overload the trimmer by jamming it into overgrown turf in one pass—take small, shallow passes instead. When you finish, release the switch, let the motor stop completely, set the trimmer down, and remove the battery pack on cordless models. For dedicated power edgers, Lowe’s guidance is similar: start with a shallow setting, run the wheels on the concrete side when possible, and always turn the machine off before adjusting anything.

Common Mistakes That Ruin a Clean Edge

Most bad edges come down to a handful of fixable errors. Pushing too hard into the soil creates jagged cuts and wears out your line fast. Moving too fast leaves wavy, uneven borders. Tilting the head away from vertical cuts a sloppy channel instead of a crisp one. And trying to chew through wet grass or thick overgrowth in a single pass just stalls the motor and tears turf.

Take your time, keep the head upright, let the tool do the work, and your borders will look professionally maintained. If you’re shopping for a new tool, our tested roundup of top electric trimmer edger picks covers the models worth your money.