How To Use A String Trimmer

Using a String Trimmer Safely

The first and most important part of learning how to use a string trimmer is to check your safety precautions. 

Make sure you check the area before you start trimming. Remove anything and everything from the area - if you hit any debris while trimming, you’re very likely to send it flying.

Once you've learned how to use a string trimmer, check out our reviews of the ​best corded electric string trimmer​.

The main safety points to be aware of are:

  • Read the manufacturer's instructions and follow them.
  • Check the trimmer and extension cord for damage before using it - every time. Do not use the trimmer if there is any visible damage to either the trimmer or the extension cord.
  • Never allow children to operate the trimmer, or be nearby when you are trimming.
  • Always wear a dust mask, safety glasses, gloves and ear protection.
  • Switch off & unplug the trimmer before cleaning or maintenance.

Read more on how a string trimmer works.

String Trimmer Type

There are different types of string trimmers:

  • Gasoline (powered by a gasoline engine)
  • Corded electric (powered by an electric motor, needs to be plugged into a power socket)
  • Cordless electric (powered by an electric motor, has a battery so doesn't need plugged in while in use)

The different types of trimmers are quite similar to use, except for the obvious differences caused by the motor type. Corded electric trimmers are the lightest, gasoline trimmers are the heaviest, with cordless electric string trimmers somewhere in the middle. Read more about gasoline vs electric string trimmers here.

There are also 2 sub-types of string trimmer:

  • Straight shaft
  • Curved shaft

Straight shafted trimmers tend to be more expensive, but generally are more flexible, with the ability to attach different heads for different jobs. Curved shaft trimmers tend to be lighter weight, and may be easier to use. You can read more about curved vs straight string trimmers here.

What Type Of Line Do I Use?

The next thing to learn about using a string trimmer is the different line types:

String trimmers use monofilament nylon lines for cutting, which you can easily buy in spools from hardware stores. The line you will use depends on your application and the type of string trimmer you have.

Long Lasting Trimmer Line

High powered gas string trimmers use heavier gage lines, usually between 0.085" - 0.105" thick. This allows them to cut through heavier vegetation in overgrown areas with ease. The heavier gage line lasts longer, as it is stronger, and does not tangle or break when it cuts through heavier vegetation.

Lighter Gage Line

Lighter gage line tends to be supplied with electric trimmers, and some cheaper gas powered trimmers. They are suitable for trimming lighter grass growing around the edges of the garden, the curbs and the edges of flower beds. Lighter gage line is usually around 0.065" thick, so it is better not to use it for heavier-duty trimming, as it will not last very long before needing to be replaced.

Learn more about different string trimmer line types here.

Spin Direction

You might not have considered this, but spin direction is important

One of the most important things you need to know about how to use a string trimmer is the spin direction. A lot of people struggle with this. Think about how a circular saw works: It cuts the wood spinning in one direction and ejects the saw dust. Similarly, the string trimmer ejects the debris from one side.

Figure out which direction your trimmer spins (usually clockwise), and plan your work around this. You don’t want to get the debris back on to the path you will be cutting on, or worse, fling it towards windows, people or pets!

Cutting Techniques

The fun part!

Many people assume that to properly use a trimmer, all you must do is let it hover and cut the grass. This is a mistaken view, however. If you do this, often, it will scald your lawn, and you do not want that. There are a few techniques that will help you to get the most out of your trimmer.


This is a technique that should be used along curbs, retaining walls, trees or fences. If you just hold the tool over the grass, it will show. The grass will be slightly shorter than the mowed grass which will look unkempt.

To taper, all you do is hold the tool at an angle; in other words, slightly tilt the strings so that they are cutting toward the curb/tree/fence/retaining wall.


You should try this when cutting in longer grass. Pretend you are an old-timey peasant busy gathering the harvest. Swing the trimmer in a shallow U motion, back and forth. This will result in a more even overall cut.


Use this technique when a surface is parallel to the grass, for example, driveways or paths. Turn the strings so that they are vertical and walk along the edge, creating a nice clean edging cut.


If you have ever felt annoyed by weeds or grass growing in cracks in the pavement, then this technique will work for you. Hold the tool so that the strings are flush with the hard surface and aim for the base of the plant. This will cut it off at the base and spare you a headache.

Additional Tips

Miscellaneous advice

Now that you aren’t scalping your poor lawn, you are going to find that using your weed whacker will be the highlight of your gardening schedule. Before we move on, there are a few tips that you need to keep in mind when using your trimmer.

If you have a "bump feed"-type string trimmer, and your string is beginning to wear down, simply hold the trimmer to the ground, running it at full speed. Allow the string to hit the ground, and it will extend the new string.

Be careful when cutting around trees. If the string slices through the bark, it could kill the tree. The bark of a tree is what protects the channels carrying water to various parts of the tree. Destroy the bark and you could destroy the tree.

By the way, you can also edge your lawn using a string trimmer. The difference between a string trimmer and an edger can be found here.

How To Restring Your Trimmer

Easier than it seems

Switch off your trimmer and remove the spool from the head. Cut an 8-foot piece of string. Thread the string through the hole in the spool and pull the ends even. Wind the string in the direction of the arrow that is on the head of the spool.

Fasten the ends into the notches that should be at the edge of the spool.

Put the spool back on the head, cut make sure that you thread the ends through the holes on the spinning head. If you have a self-winding head, just feed the string through the spool then rotate the head to wind it up.

Keep in mind that there are different types of trimmers out there. Be sure to read the instruction manual in case there are any special requirements, since each brand is different.


Putting it all together

Always make sure that you keep your safety in check and the safety of others when you’re using the string trimmer. Be careful not to hit the cable if you’re using an electric trimmer and clear the area before you start using the string trimmer.

Using a string trimmer is easy, all you have do is get the hang of it. Once you have mastered the various techniques, you will have the neatest yard around.

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How Does a String Trimmer Work - November 1, 2019

[…] string trimmer is a wonderful tool. It is versatile, maneuverable and useful for all kinds of jobs in your yard. […]


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