Many homeowners use the terms “edging” and “trimming” interchangeably, but they describe two different lawn-care tasks. Trimming cuts grass in areas a mower cannot reach, such as around fence posts, trees and garden beds. Edging creates a clean vertical cut along sidewalks, driveways and patios, separating the lawn from hard surfaces. A string trimmer can handle both jobs, though the approach and results differ. For choosing a trimmer, see our string trimmer buying guide.
What Trimming and Edging Actually Mean
Trimming is the job of cutting grass and light weeds that grow where a lawn mower cannot fit. This includes around trees, along fences, near flower beds and against walls. The cutting head of a string trimmer spins a nylon line parallel to the ground, slicing through vegetation horizontally. According to the Greenworks 24V 12-inch string trimmer operator manual, the machine is set up to cut grass with a spinning line, and the guard and line cut-off blade help maintain a consistent cutting diameter.
Edging, by contrast, cuts a vertical trench along the border between the lawn and a hard surface. The goal is a sharp, defined line that stops grass from creeping onto the walkway. The Ohio State University Extension notes that many handheld trimmers are designed to incorporate attachments such as brush-cutting blades, cultivators and edgers. If you want to edge regularly, check whether your trimmer system offers an edger attachment, and follow that attachment’s manual. Our attachment-capable trimmer guide explains how these systems work.
How a String Trimmer Handles Both Jobs
A string trimmer’s spinning line is effective for trimming grass and weeds in hard-to-reach areas. The operator holds the trimmer head roughly horizontal and sweeps it side to side. The Greenworks manual explains that the trimmer head uses a bump-feed mechanism: tapping the head on the ground releases more line, and a cut-off blade on the guard trims the line to the set cutting diameter. This keeps the cutting width consistent, either 12 inches for a larger cutting area or 10 inches for greater runtime, depending on how the cut-off blade is positioned.
The Greenworks manual describes trimming; it does not describe an edging position. So before you use any trimmer to edge, check whether its own manual allows it, and keep the guard in place as instructed. Ohio State notes that some trimmers accept edger attachments.
| Task | String Trimmer Approach | Notes |
|---|---|---|
| Trimming around obstacles | Hold the head horizontal, sweep side to side, bump-feed line as needed. | The guard and line cut-off blade maintain a consistent cutting diameter. Remove visible stones and debris first to avoid thrown objects. |
| Light edging along hard surfaces | Only if your trimmer’s manual describes an edging position. | Otherwise use an edger attachment approved for your power head, if one exists. |
| Heavy edging or creating a new edge | Use the tool your manual approves for the job. | Ohio State says to use attachments only as they were designed to be operated, and not to cut near hard objects with rigid blades. |
Safety and Protective Gear
Both trimming and edging throw debris at high speed. The Ohio State University Extension emphasizes that contact from rotating cutters and flying debris can cause serious injury, including cuts and lacerations. The organization recommends keeping bystanders at least 50 feet away. The Greenworks manual also stresses the importance of wearing correct clothing, protective gloves and safety glasses.
Ohio State advises wearing safety glasses with side shields or goggles, plus a face shield or screen for additional protection. Ear protection is necessary because of the high noise levels produced by the engine or motor. Leather gloves protect hands from cuts and abrasions, and sturdy leather work boots or hard-soled shoes shield the ankles and feet. Long pants and a snug-fitting long-sleeved shirt help protect skin from flying debris. The Greenworks manual similarly instructs users to wear protective gloves and safety glasses.
Maintenance and Care
Keeping a string trimmer in good condition helps it perform both trimming and light edging tasks reliably. The Greenworks manual provides specific maintenance steps for its cordless model. After each use, clean the machine with a moist cloth dipped in neutral detergent; do not use aggressive solvents. Keep the trimmer head free of grass, leaves and excessive grease, and ensure the air vents are clear to prevent overheating. Do not spray water onto the motor or electrical components.
The line cut-off blade on the guard can become dull over time. The manual notes that if the line does not cut well, the blade can be sharpened with a file or replaced. The cutting diameter can be adjusted by turning the cut-off blade 180 degrees: set to 12 inches for a larger cutting area or 10 inches for greater runtime. When the line wears short, bump the trimmer head on the ground to advance fresh line. Replace the spool or rewind line only with nylon cutting line of 0.065 inch (1.65 mm) diameter, as specified in the manual.
The Ohio State University Extension adds general maintenance guidelines that apply to any trimmer: review the operator’s manual for recommended service, maintain proper lubrication of moving parts, and inspect, adjust or replace all deflector guards and safety features. Before storing the equipment for extended periods, drain the fuel tank (for gas models) and run the engine until it stops, or remove the battery pack for cordless models. Always shut off the machine and disconnect the spark plug or remove the battery before performing any maintenance.
Frequently asked questions
Can I use a string trimmer as an edger?
Only if its manual says so. The Ohio State University Extension notes that some trimmers can accept edger attachments. Check your trimmer’s manual to see whether it allows edging and which attachments it supports.
What safety gear do I need for trimming and edging?
According to the Ohio State University Extension, you should wear safety glasses with side shields or goggles, a face shield, ear protection, leather gloves, sturdy boots, long pants and a long-sleeved shirt. The Greenworks manual also calls for protective gloves and safety glasses. These precautions protect against flying debris, noise and contact with the spinning line.
How do I keep the line from breaking too often?
The Greenworks manual advises cutting with the tip of the line and avoiding contact with stones, walls and other hard objects. Advance the line regularly to maintain full cutting width, and use only the recommended 0.065-inch nylon line. The manual’s troubleshooting table also says to sharpen the cut-off blade with a file or replace it if the line does not cut well. See our trimmer line guide for more.
For more help choosing the right tool for your yard, see our string trimmer and edger guides.
