Greenworks 21142 Review 2026 ▷ 5-Amp Electric String Trimmer

The first thing you notice about the Greenworks 21142 is its cutting width. At 15 inches, it is wider than most corded electric trimmers at this price — the BLACK+DECKER ST8600 cuts 14 inches, many budget models cut 13 inches. For a homeowner who trims the perimeter of a standard suburban lot weekly, that extra inch per sweep translates to meaningfully fewer passes and less time working. It is a simple advantage, but a real one.

Greenworks built the 21142 with a 5-amp motor (versus the ST8600's 6.5-amp), a dual-line bump-feed head, and a pivoting cutting head that serves as both trimmer and inline edger. At the price point it occupies — typically $60–80 — it represents one of the better value propositions in the corded electric trimmer category. This review examines whether the wider cutting path and Greenworks brand backing justify the choice over its direct competitors.

Who the Greenworks 21142 Is Best For

The Greenworks 21142 suits homeowners with yards where cord management is manageable and where grass stays relatively well-maintained — meaning weekly or bi-weekly trimming sessions rather than occasional heavy-duty work on overgrown sections. If you mow consistently, the 21142 handles the subsequent perimeter trimming without asking you to push its motor into stress.

It is a particularly strong fit for homeowners who are evaluating their first string trimmer purchase and want to understand whether a corded electric tool fits their workflow before investing in the battery or gas category. At $60–80, the entry cost is low, and the tool teaches you whether you find cord management workable in your specific yard before committing $150–250 to a battery trimmer platform.

It is not the right tool for heavy weeds, thick brush, or properties where the nearest outdoor outlet requires a cord run that makes the tool impractical. For those situations, the Makita XRU02Z battery trimmer or a gas trimmer provides the power and freedom of movement that the situation demands.

Greenworks 21142 Specifications

Specification	Value
Motor	5 amps, 120V corded electric
Cutting Width	15 inches
Trimmer Line Diameter	0.065 inch (dual line)
Line Feed System	Bump feed
Shaft Type	Straight
Edger Conversion	Yes — pivoting head
Weight	5.1 lbs
Power Source	Corded — requires extension cord
Warranty	4-year limited
ASIN	B00K9DXE8A

Two specifications stand out compared to competitors. First, the straight shaft — less common on budget corded trimmers, which typically use curved shafts. A straight shaft provides better reach under decks, low fences, and tight garden borders where a curved shaft makes the angle awkward. It also runs the line at a more consistent plane relative to the cutting surface, which many users find produces a cleaner edge line. Second, the 4-year warranty is longer than the 2-year coverage typical in this category. Greenworks backs their tool lineup aggressively on warranty, which matters given that a corded electric motor's failure mode — though rare — is not field-repairable.

Performance Analysis: Real-World Results

The 15-inch dual-line cutting head is the defining performance characteristic. Using two strands of line instead of one provides a modest boost to cutting efficiency — each strand contacts the vegetation from a slightly different position, reducing the chance of grass bending away from a single-line cut. The bump-feed mechanism is straightforward: when line runs short, tap the head against the ground while the motor is running and the spool advances a measured length of fresh line. This takes practice to time correctly — tap too early and you advance line that isn't yet worn, wasting material; tap too late and you lose a few seconds of cutting speed while the head spins with short line.

The 5-amp motor performs within its design parameters on residential grass maintained at normal heights. At typical trimming heights (2–4 inches of grass beyond the mow line), the motor maintains head speed consistently and the 15-inch path covers ground efficiently. A typical suburban lot with 6,000–8,000 square feet of perimeter to trim takes approximately 20–25 minutes at a comfortable working pace.

The straight shaft is a genuine advantage over the curved-shaft BLACK+DECKER ST8600 for two specific tasks. First, reaching under overhanging deck boards or low horizontal fences — where a curved shaft would require bending uncomfortably to get the head into the space, the straight shaft allows a natural reach that keeps the cut parallel to the ground. Second, edging alongside raised beds or low retaining walls — the straight shaft positions the cutting head at a better angle for a consistent vertical cut without the operator having to compensate for the curved shaft's geometry.

The pivoting edger conversion works well for standard sidewalk and driveway edging. Rotate the head to the vertical position, position the guide against the pavement edge, and work at a steady pace. The 15-inch cutting width means that in edger mode, you are cutting 15 inches of vertical grass height per pass — more than adequate for standard edging tasks. The pivot mechanism is firm enough to hold position during use but rotates easily when you want to convert.

Pros and Cons

How It Compares to the Competition

The Greenworks 21142 sits in a three-way corded electric market alongside the BLACK+DECKER ST8600 and several entry-level budget options. The decision between the Greenworks and the BLACK+DECKER comes down to which specification matters more for your specific yard.

Model	Power	Cut Width	Shaft	Line Feed	Warranty
Greenworks 21142	5A	15 in	Straight	Bump	4 years
BLACK+DECKER ST8600	6.5A	14 in	Curved	Auto	2 years
Makita XRU02Z	18V battery	13 in	Straight	Bump	3 years

The Greenworks wins on cutting width, straight shaft geometry, and warranty length. The BLACK+DECKER wins on motor power and automatic line feed convenience. For yards with normally maintained grass and a homeowner who learns to use bump-feed correctly, the Greenworks 21142 is the better daily-use tool. For yards with occasional heavy patches or a homeowner who prefers zero line-management involvement, the ST8600's automatic feed justifies the trade-off of a slightly narrower cut path.

The Makita XRU02Z enters the comparison as the cordless alternative. At 18V, it delivers less raw power than either corded option, but its freedom from the extension cord is meaningful for larger yards or properties where outlet placement makes cord use impractical. At tool-only pricing (battery sold separately), it is also a compelling option for homeowners already in the Makita battery ecosystem.

Maintenance Tips

The Greenworks 21142 requires less maintenance than any gas trimmer but benefits from a few consistent practices that preserve motor health and cutting performance.

Bump-feed technique: The most impactful skill for Greenworks 21142 owners to develop is correct bump-feed timing. Tap the head against firm ground (not grass, which absorbs the impact) while the motor is running at operating speed. A firm, deliberate single tap advances the correct amount of line. Repeated rapid taps in quick succession can advance too much line at once, causing the excess to break off immediately under centrifugal force — wasting line and requiring another bump cycle. Practice on a hard surface like a concrete path or driveway edge to develop the right feel for the tap force and timing.

Head cleaning: The cutting head collects grass, debris, and occasionally sap and soil around the spool housing and line exit eyelets. After each use, remove the spool (press the tabs on each side of the spool cap and pull it free), shake out accumulated debris, and wipe the inner housing with a dry cloth. Debris packed into the spool housing can interfere with the bump-feed mechanism, causing the spool to stick rather than advance properly. This cleaning takes 2–3 minutes and prevents the most common non-wear failure mode in bump-feed heads.

Motor ventilation: The motor housing has ventilation slots that draw cooling air over the motor windings during operation. After each use, blow out these slots with compressed air or a dry paintbrush to remove accumulated grass dust and fine debris. A motor that runs hotter than designed because its vents are clogged experiences accelerated insulation wear on the windings — the primary failure mode in corded electric motors over time.

Long-term storage: For winter storage, clean the tool thoroughly and store it in a dry location out of direct sunlight. Unlike gas tools, there are no carburetors to drain or fuel system concerns. The extension cord benefits from being stored loosely coiled in a dry location — tight coiling stresses insulation at the bend points, and cold outdoor storage makes the cord jacket brittle and prone to cracking over time.

Frequently Asked Questions

Frequently Asked Questions

What trimmer line size does the Greenworks 21142 use?

The Greenworks 21142 uses 0.065-inch diameter dual-line trimmer line. This is a standard gauge widely available at hardware stores, home improvement centers, and online. Greenworks sells compatible pre-wound replacement spools, but any 0.065-inch universal trimmer line in a round profile works with the bump-feed head. Avoid using heavier line (0.080-inch or above) — the motor is sized for 0.065-inch and a thicker line puts unnecessary strain on the head and motor. For refilling the spool manually, measure and cut two equal lengths of 0.065-inch line, find the notch in the center of the spool, fold the line at the midpoint, wind both strands in the direction indicated by the arrow on the spool body, and thread each end through the exit eyelet before replacing the spool cap. Most users find buying pre-wound replacement spools easier — the cost difference over a season is minimal.

Can the Greenworks 21142 handle thick weeds and overgrown areas?

The 21142 handles standard residential weeds — dandelions, plantain, clover, grass that has grown 4–6 inches beyond the mow line — without significant difficulty. Its 5-amp motor runs the 15-inch dual-line head at adequate speed for typical maintenance conditions. Where it shows limitation is on very thick weed stems (over 3/8 inch in diameter), dense brush, or sections that have gone several weeks without trimming and developed woody, established growth. In these conditions, the motor reduces head speed noticeably and line consumption increases. For reclamation work or persistent heavy growth, a 40V battery trimmer or gas trimmer with a heavier line gauge is more appropriate. The 21142 is at its best as a weekly or bi-weekly maintenance tool rather than an occasional-use heavy-duty tool.

Does the Greenworks 21142 work as an edger?

The 21142 includes a pivoting head that rotates 90 degrees to position the dual-line cutting head vertically for inline edging along sidewalks and driveways. Unlike some trimmer-to-edger conversions, the Greenworks design uses a straight shaft that places the vertical cutting head at a comfortable working angle for edging. The result is adequate for regular residential edging maintenance — defining a clean line along pavement edges and keeping turf from encroaching onto hardscaping. The conversion takes a few seconds and requires no tools. For the sharpest possible edge definition, a dedicated rotary edger with a metal blade produces a more precise cut, but for homeowners who edge regularly (every 1–2 weeks), the 21142 edger mode is a practical substitute that eliminates the need for a separate tool purchase.

How long is the power cord on the Greenworks 21142, and what extension cord do I need?

The Greenworks 21142 has an 8-inch integrated power cord that connects to your extension cord. For the extension cord itself: the 21142 draws 5 amps at 120V, making it compatible with 16-gauge (AWG 16) outdoor-rated extension cords for runs up to 100 feet. A 100-foot 16-gauge outdoor extension cord costs approximately $25–35 and covers the full perimeter of most residential lots. If using a longer cord (over 100 feet), move up to 14-gauge to prevent voltage drop. Always use extension cords rated for outdoor use — look for a 'W' designation on the cord jacket indicating weather resistance. Never use household indoor extension cords with outdoor power tools: they lack the insulation and weatherproofing required for safe outdoor use.

Is the Greenworks 21142 better than battery trimmers for the money?

For a homeowner whose yard has accessible outdoor power outlets and who wants the lowest total cost of ownership, the Greenworks 21142 is genuinely more economical than comparable battery trimmers. A battery trimmer in the 20V class (CRAFTSMAN CMCST900D1, WORX WG163) costs $120–170 with battery and charger, while the 21142 is typically $60–80. Over 5 years, the battery trimmer requires one or two battery replacements at $40–60 each, while the 21142's only recurring cost is replacement spools at $5–8 each. The trade-off is cord management — running an extension cord adds 2–3 minutes to setup and requires you to keep the cord behind your working path. If cord management is genuinely inconvenient in your yard (large property, obstacles, no convenient outlet placement), the battery trimmer's cordless convenience justifies the premium. If your yard is compact enough that a 50-foot cord reaches everything easily, the Greenworks 21142 is the smarter economic choice.