How to Use an Edge Trimmer? | Edging Mode Step by Step

One wrong angle with a string trimmer in edging mode can gouge the turf or scatter debris across a freshly planted bed. The fix is a specific grip change and walking direction that most owners never learn. Here is how to set up the tool, hold it correctly, and cut a crisp edge every time — without fighting the machine.

What Makes a String Trimmer Work as an Edge Trimmer

Most cordless string trimmers sold today, including the Black & Decker LSTE525, EGO ST1500F, and Worx WG163M, include a head that rotates 90 degrees and a flip collar that locks it into a vertical cutting plane. The trimmer head and line then function like a vertical blade that carves a clean line between the lawn and the sidewalk or flower bed. The same mechanism exists on 56V EGO models and 18V platforms from Ozito, so the core steps are the same across brands.

Prep the Lawn First

Mow the grass to about 2.5 inches before you edge. Cutting more than the top third of the blade stresses the plant and leaves a ragged edge. Mark the intended edge line with a measuring tape or a straight stick if you need a precise boundary. This step is easy to skip, but it is the difference between a straight driveway edge and a wandering curve that takes twice as long to fix.

The Edging Grip You Probably Haven’t Tried

The single biggest mistake people make is keeping the trimmer right side up. You need to flip the entire tool upside down. Hold the side handle, not the top shaft, and rest your thumb on the trigger. The deflector shield must face toward your body. This grip looks awkward the first time but gives you far better control because your thumb on the trigger lets you feather the speed while your other hand guides the direction. To see the exact setup on that specific model, a video walkthrough of the LSTE525 shows the head rotation and collar lock in detail.

Direction of Travel: Which Way to Walk

The spinning line throws debris in the direction of its rotation. If your trimmer spins clockwise — the most common direction on cordless models — edge by walking left to right. That pushes the clippings and loose soil away from the lawn and onto the hard surface, where you can sweep them up easily. If your trimmer spins counterclockwise, walk right to left. Moving with the spin instead of against it throws everything back into the grass and forces you to fight the tool’s torque the whole way.

Angle and Line Length Matter More Than You Think

Hold the spinning line at a 90-degree angle to the ground. Any slope carves an uneven trench and can dig into soft soil. Keep the line extended about 3 to 4 inches from the trimmer head — roughly halfway out. A line longer than 4 inches whips unevenly and creates a ragged cut. A line shorter than 3 inches loses most of its cutting power and forces you to push the head closer to the edge, which increases the risk of nicking the concrete or burying the blade guard in the dirt.

Take Small Bites, Not Long Sweeps

Edging moves fastest when you take small bites. Guide the trimmer along the edge in short, smooth passes of about two to three feet. Trying to edge an entire driveway in one continuous sweep causes the line to dig deeper as you go, creating a trench that gets wider and deeper toward the end. Small bites also let you steer around roots, curbs, and sprinkler heads without jerking the tool.

Common Mistakes That Ruin a Good Edge

• Wrong direction: Walking with the spin throws debris inward and forces you to edge twice.
• Poor angle: A slanted line digs deeper on one side and leaves the other side uncut.
• Long line: Over four inches whips unevenly and produces a ragged edge.
• Skipping the guard: Removing the blade guard increases the risk of debris hitting your legs or damaging plants.
• Looking at the head: Staring at the spinning line instead of your walking path makes the edge wander.

Recommended Trimmer Settings at a Glance

Choosing the right tool for the job makes a real difference. If you’re still shopping, our roundup of the best combination trimmer and edger models covers tested options that switch modes without tools.

How to Clean Up After Edging

The debris kicked onto the sidewalk or driveway is part of the point — it keeps the lawn clean. Let it dry for a few minutes, then sweep or blow it back into the grass, where it breaks down as natural mulch. Do not leave the clippings on hard surfaces, because they stain concrete and can be slippery when wet. A leaf blower makes quick work of this if you have one, but a stiff broom works just as well.

How to Edge Near Flower Beds Without Killing Plants

When the edge runs next to a garden bed, walk the opposite direction so the debris shoots into the yard instead of onto the plants. Stop the trimmer before you cross the boundary line at each end of the bed — walking through the turned-off tool resets your grip and avoids accidental nicks on stems. If the bed is full of delicate annuals, consider holding the trimmer at a slightly shallower angle so the line skims the soil surface rather than digging into it.

Safety Equipment You Should Not Skip

• Safety glasses or goggles
• Long pants and closed-toe shoes
• Gloves
• Ear plugs (hearing damage accumulates fast with power tools)
• Face mask if grass or pollen triggers allergies

Never operate a gas-powered trimmer indoors or in a garage — the carbon monoxide is deadly. Keep children and pets at least 50 feet away from the cutting area. The Black & Decker manual and the EGO manual both emphasize that the blade guard and deflector shield must stay in place at all times, and that the tool should never be used in rain or wet grass.

Final Edging Checklist