String Trimmer vs Edger: Do You Need Both?

A dedicated edger gives the cleanest, straightest edge along sidewalks and driveways, because its steel blade cuts a vertical slot through turf and soil at a fixed depth while wheels guide it along the pavement. A string trimmer can also edge, by turning the head sideways, and for most small and medium yards it does a perfectly good job of maintaining an existing edge. You need both only if you have a lot of hardscape to edge, aggressive creeping grasses such as Bermuda, St. Augustine or zoysia spilling onto concrete, or you want a sharp, sports-field look every week. Everyone else can buy a good trimmer, learn to edge with it and skip the second tool.

Part of our Lawn Care guide →

In this guide

1. String Trimmer vs Edger at a Glance
2. How a Dedicated Edger Works
3. How a String Trimmer Edges
4. Decision Factors
5. Can a String Trimmer Replace an Edger?
6. Which Should You Choose?
7. Edging Order and Timing
8. Frequently Asked Questions

String Trimmer vs Edger at a Glance

Factor	String trimmer	Dedicated edger
Cutting element	Spinning nylon line	Rigid steel blade, typically 7.5 to 9 inches
Cut direction	Horizontal for trimming; vertical when edging	Vertical only
Edge quality	Good with practice; can wander or scalp	Very straight, clean and consistent
Depth control	By hand	Adjustable blade depth, set once
Overgrown edges	Slow; line wears fast on concrete	Cuts through thick runners and sod quickly
Other jobs	Trimming around obstacles, fences, beds, slopes	Edging only (some can trench for bed edges)
Storage and cost	One tool, compact	Second tool to store and maintain
Best for	Most homeowners, small and medium yards	Large hardscape runs, creeping grasses, perfectionists

How a Dedicated Edger Works

Stick or walk-behind edgers spin a flat steel blade in a vertical plane. A guide wheel rides on the sidewalk or driveway while the blade cuts into the turf right at the concrete’s edge. You set the blade depth, usually up to about 1.5 to 2 inches on many models, and the wheels keep the cut straight and consistent. Walk-behind edgers have a wheeled frame and are the easiest to steer in a straight line; stick edgers look like a trimmer with a blade housing and small wheel at the end.

Because the blade is rigid, an edger cuts cleanly through thick stolons and rhizomes that creep over concrete. That is why edgers are so common in the South, where Bermuda and St. Augustine runners can cover a sidewalk edge in weeks. It also leaves a small trench between grass and pavement, which slows regrowth and looks crisp for longer than a trimmer edge.

Downsides: an edger is a single-purpose tool, it throws debris and sparks if the blade touches concrete, and blades wear and need replacing. For current models, see our roundup of the best lawn edgers.

How a String Trimmer Edges

A string trimmer, also called a weed eater or weed whacker, spins one or two lengths of nylon line at high speed. For trimming, the head is held parallel to the ground. For edging, you rotate the trimmer so the head is vertical and the line cuts a slot along the edge of the pavement. Many trimmers have a rotating head or shaft and a small edging guide wheel to make this easier; others require you to turn the whole tool in your hands.

With practice, a trimmer can produce a clean edge, especially when you edge weekly or every other week so the grass never gets far over the line. It struggles more with thick runners and long-neglected edges, where line wears down quickly against concrete and the cut wanders. Our guide on how to use a string trimmer covers the edging technique in detail.

Decision Factors

How much hard edge you have

Measure your sidewalks, driveway, curbs and patio edges that border lawn. A small lot with a short front walk may have under 100 feet of edge; a corner lot with a long driveway and curbside sidewalk can have several hundred. The more linear feet you edge, the more an edger saves in time, line and wrist strain.

Your grass type

Warm-season grasses that spread by above-ground runners, such as Bermuda, St. Augustine, zoysia and centipede, creep across pavement aggressively. Edgers handle them far better. Cool-season bunch-type grasses such as tall fescue spread slowly sideways, and a trimmer keeps them neat with little effort. Kentucky bluegrass spreads by underground rhizomes, which is somewhere in between.

How crisp you want it

A trimmer edge looks neat from the street. An edger edge looks like a golf course: a sharp, vertical line with a small gap of exposed soil. If that finished look matters to you, a dedicated edger is the tool.

Bed edges vs sidewalk edges

Edgers are designed to ride along hard surfaces. For soft edges between lawn and flower beds, there is no pavement for the guide wheel. Some edgers can tilt to cut bed edges or trench, but many homeowners use a half-moon manual edger to cut a bed edge once a season and a trimmer to maintain it. Physical landscape edging, covered in our guide to installing landscape edging, removes much of that maintenance entirely.

Power source and weight

Both tools come in gas, corded electric and battery versions. Battery platforms are appealing here because one battery can power both a trimmer and an edger from the same brand. If you are weighing fuel types, our comparison of a gas vs battery string trimmer applies to edgers as well: gas suits large properties and heavy use, battery suits most suburban lots.

Budget and storage

A second tool means more money, more garage space and another blade or engine to maintain. If space is tight, an attachment-capable power head (a split-shaft trimmer that accepts an edger attachment) or a combo kit is a good compromise.

Safety and ease of use

Both tools throw debris, but in different ways. A trimmer turned vertical flings grit, small stones and clippings sideways and can scuff car paint, windows and siding if you are careless with direction. An edger blade sends a narrow stream of soil and pebbles out of its guard and will spark and chip if it touches concrete or hits a buried rock. Edgers are generally easier for beginners to run straight, because the wheels do the steering; trimmers demand more arm control and get tiring on long runs. Either way, wear safety glasses, hearing protection with gas models, long pants and sturdy shoes, and keep children and pets away while you work.

Ongoing upkeep

Trimmers consume line, and edging against concrete uses it faster than trimming grass, so expect to reload more often if the trimmer does both jobs. Edger blades last longer but need occasional sharpening or replacement and a check of the blade bolt and belt or shaft. Gas versions of either tool add fuel mixing, spark plugs and air filters to the list, while battery tools need little beyond keeping the batteries charged and stored indoors over winter.

Can a String Trimmer Replace an Edger?

For most yards, yes. The keys to edging well with a trimmer:

• Edge frequently. Weekly or every other mowing keeps the job light and the line clean.
• Rotate the head fully vertical and keep it there. A tilted head scalps the lawn or gouges a sloped edge.
• Use a guide. Rest the trimmer guard or an edging wheel on the pavement and walk at a steady pace.
• Watch the debris direction. Position yourself so clippings and grit fly onto the pavement, not toward you or your house.
• Use heavier, durable line for edging, within your trimmer’s recommended range. Twisted or square profiles cut grass well but wear on concrete; round line holds up better against pavement.
• Wear eye and hearing protection, long pants and closed shoes.

Where a trimmer falls short is the reclaim job: cutting back several inches of grass that has grown over a neglected sidewalk, or keeping up with Bermuda in midsummer. For those, a dedicated edger, or a single rental day, is worth it.

Which Should You Choose?

• If you have a typical suburban lot with a short walk and driveway and cool-season grass: buy a string trimmer and use it for both jobs.
• If you have warm-season, runner-type grass and lots of concrete edges: get both, or a trimmer plus edger attachment on a shared power head.
• If you want sharp, professional-looking edges every week: add a dedicated edger.
• If your edges are mostly lawn-to-bed rather than lawn-to-pavement: use a trimmer and a manual half-moon edger, or install permanent edging.
• If you are reclaiming long-neglected edges once: rent an edger for a day, then maintain with a trimmer.

Shopping for a trimmer that will also handle edging? Look for a rotating head or edging guide wheel, and compare options in our roundups of the best string trimmers and the best cordless string trimmers. For the rest of your lawn routine, from mowing height to feeding schedules, see our lawn care guide.

Edging Order and Timing

Most pros mow first, then edge, then trim around obstacles, then blow clippings off hard surfaces. Edging after mowing means you can see the line clearly and grass height is uniform. In the growing season, edge every one to two weeks; in cooler months, once every three or four weeks is usually enough. Keep edger blades sharp and replace them when they become rounded, and check trimmer line length and condition before each session. Sweep or blow the cut soil and grass off the pavement afterward so it does not wash into storm drains.