String trimmers, also called weed wackers, cut the grass your mower cannot reach along fences, walks and garden beds; weeders pull weeds from the soil. The right replacement line and head keep those edges trimmed without fighting broken string or a poor fit. For scattered weeds you want out by the roots, a stand-up weeder saves bending.
Replacement string trimmer heads: get the fit right
Buy a universal gas trimmer replacement head for a compatible gas trimmer with a worn head. Choose a combination line-and-blade replacement head for a machine approved for that cutting system. Match the exact trimmer, cutting head and guard combination before buying; the word “universal” alone does not establish that match.
Feed style matters because it changes how you work. Bump-feed heads advance line when tapped against the ground. Other heads feed automatically, use a control on the trimmer or take precut lengths that you replace by hand. Buy the feed system that matches your machine and the way you want to reload it.
For a cordless battery string trimmer, match replacement line to the accepted diameter range, not battery voltage. An attachment-capable string trimmer also needs the correct cutting attachment and guard. Adding a different head does not by itself turn a grass trimmer into a brushcutter.
Choose a grass-trimming head for grass and light weeds. For thicker woody growth, move to a brushcutter with an appropriate blade. Replacement blades belong with the head and machine approved to use them.
String for a weed trimmer: which size should you buy?
Line size means thickness. Start with the diameter your trimmer and head accept, then choose for the growth you cut. Bigger string is useful only when the machine can drive it: oversized line can jam the head, strain the motor and shorten cordless runtime.
| String trimmer line diameter | Approximate metric diameter | Job to match it to on a compatible trimmer |
|---|
| .065 inch | 1.65 mm | Light grass and precise work around flower beds |
| .080 inch | 2.03 mm | Routine residential lawn trimming |
| .095 inch | 2.41 mm | Thicker grass and light weeds |
For routine lawn edges, buy .080-inch replacement line when your trimmer accepts it. That is a useful match for regular homeowner trimming. Choose .065-inch line for an approved light-grass setup, and .095-inch line for thicker grass on a machine that accepts that diameter.
Can you use any replacement string? Correctly sized generic line works in many trimmer heads, but the diameter must fall within the accepted range for both the machine and head. A head that holds thicker line does not increase the trimmer’s power.
Shape comes after diameter. Round line resists breakage around concrete and fences, making it a good choice along hard edges. Square line has four cutting edges and cuts thick vegetation faster than round line. Choose for what the string hits as well as what it cuts.
Montana winter storage gives you a reason to inspect last season’s line before spring trimming. Replace brittle, damaged or discolored string. Buy roughly a season’s supply rather than a large spool that will sit through several winters. In the Flathead Valley, use the May 19–September 22 frost-free window to plan regular yard upkeep and have fresh line ready before the first round.
How to replace grass trimmer string
Shut the trimmer off completely and clean dirt and debris away before opening the head. For a removable-spool design, remove the spool, fit new line in the correct diameter and loading length, then secure the head. A fixed-line head takes precut lengths instead. Match the reload method to the head you have.
Line advancement and line replacement are different jobs. Tapping a bump-feed head releases more of the line already inside it; an empty head needs reloading. Button-fed and trigger-fed systems use their controls to advance line. Sorting out which operation you need saves taking a loaded head apart unnecessarily.
For a gas trimmer that requires 50:1 premix, choose premixed 50:1 fuel to match that requirement.
Trimming lawn edges or pulling garden weeds
Use a string trimmer to finish after mowing and work around borders and obstacles. For edging along a walk, use the machine’s edging configuration where it has one; a convertible head puts the cutting line in position for that job. Keep the mower for the main lawn, where it gives a more even finish.
Walk a Montana fence line before trimming it in spring. Snowmelt can leave the ground wet for weeks at the posts, so plan your route around firm footing. Around trees and shrubs, use mulch or garden edging to leave a strip that needs no trimming. Repeated contact with string can damage bark.
Buy a stand-up weeder for individual weeds you want to pull with their roots while reducing stooping and kneeling. That makes it useful for scattered weeds in a maintained lawn or smaller garden. In Polson, boulders, clay and gravel can change across one lot; judge the ground at each weed instead of forcing the same motion everywhere.
The Pick
Buy replacement line first for routine upkeep: .065 inch for light grass, .080 inch for regular lawn trimming or .095 inch for thicker grass, matched to your trimmer’s accepted diameter. Buy the universal gas replacement head for a compatible gas machine, or the combination line-and-blade head for an approved combination setup. Choose a stand-up weeder when the job is pulling individual weeds out by the roots.
Frequently Asked Questions
What size string does a weed trimmer take?
Use the diameter approved for both your trimmer and its cutting head. For a machine that accepts .080-inch line, that’s a useful choice for routine lawn trimming. Going thicker can strain the motor, while line that’s too thin can break quickly under the power of a larger engine.
How do you put new string in a weed trimmer?
Shut your weed trimmer off completely, remove the battery on a cordless machine and clean debris away from the head. On a removable-spool design, take out the spool, load the correct diameter and length of line, then secure the head. A fixed-line head takes precut lengths instead, so the reload method depends on the head you have.
How do you edge with a string trimmer?
If your string trimmer has a pivoting edging head and guide wheel, move the head into its edging position and use the wheel to follow the walkway. A variable-speed trigger lets you ease back for control near flower beds. Keep your pace steady so you can follow the edge without swinging into the lawn.
How do you use a string trimmer?
Let the ends of the string trimmer line cut the grass instead of pushing the whole head into the growth. Work with controlled sweeps, and keep the line clear of tree bark. Wear eye protection, hearing protection and gloves before you start; the guard stays fitted for the cutting head you’re using.
What’s the best electric string trimmer for yard work?
For regular edging in a smaller yard, a lightweight electric string trimmer is often the useful choice because it’s easier to maneuver. Thicker grass calls for enough power and a cutting system suited to that growth. With a corded tool, cord reach limits where you can work; with a cordless tool, a compatible spare battery extends your available cutting time.
