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Best Way To Edge With A String Trimmer (Illustrated Guide)

Best Way To Edge With A String Trimmer (Illustrated Guide)

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Paul Brown

I learned how to edge my lawn with a string trimmer out of necessity. For some time now I have had my eye on a battery-powered edger. I’m not quite ready to pull the trigger on it though so I make do with what I have.

Best way to edge a lawn with a string trimmer: The most effective way of edging with a trimmer is by turning the trimmer on its side with the string spinning away from you and placing the shaft on your shoulder. This allows precise movement of the string along the edges as well as visual confirmation as you work.

String trimmers, weed eaters, or weed whackers as they are commonly known, are not considered the best tool for the job when it comes to edging. That being said, I have seen many homeowners and a decent number of professionals using trimmers to get the job done just fine. And I get by with this technique as well.

Let’s walk through this process and I will demonstrate exactly how this is done.

Trimmers Vs. Edgers

It’s important to acknowledge that the absolute best way to get any project done is to have the right tool for the job. When it comes to edging, no tool will give you as true and straight of a cut as an edger. That being said, it is still possible to get impressive results using a string trimmer.

I’ve used the Stihl KombiSystem for years so that’s what I’m going to be demonstrating with. But the technique is the same regardless of the brand of string trimmer that you are using.

First Things First: Direct Debris Away From You!

When you edge with a string trimmer by turning it on its side you are reducing its built-in ability to protect you from flying debris. This is because the weed guard is designed to be used in a horizontal, not vertical orientation.

Because of this, we need to make sure that debris is directed away from you. String Trimmers generally rotate clockwise but check yours first to be sure. Once you are certain of the rotation, you can determine the best direction to hold your trimmer while edging.

It’s also a really good idea to wear safety glasses or goggles while doing this.

Step 1: Rotate The String Trimmer Into An Edging Position

Rotate trimmer head for edging.

Holding the string trimmer in its normal position, rotate the shaft until the guard is up and you have a clear line of sight to the string. You will notice that as you rotate it, the angle of the trimmer head changes. Our goal is to get the trimmer head close to 90 degrees with the surface.

You will notice that by simply rotating the head over we do not get a true 90-degree angle. In order for this to work, we need to raise the back end of the string trimmer. That’s where the next step comes in.

Step 2: Shoulder-Mount The Trimmer Shaft To Edge

This is a little misleading because you generally are not actually resting the trimmer shaft on your shoulder. What you are doing is holding the shaft in your hand and resting your arm in this upward position near your shoulder.

The shoulder mount technique allows for the trimmer to be at a 90 degree angle when edging.

Be mindful with gas-engine trimmers that you do not put the engine too close to your head so as to avoid burns. I’ve never had an issue with this to be honest since you aren’t actually holding it right next to your ear, it is several inches away. Still, be mindful of this.

You will notice that this position will put the string at just about the 90-degree angle that we are looking for. While the position may look awkward it is surprisingly comfortable. The back end of the trimmer is simply resting on your hand.

Note: Hearing protection is a good idea anytime you are working with gas-engine yard tools but especially when holding one this close to your ear. Click here to read about the noise-canceling headphones that I use anytime I’m working with loud yard engines.

Step 3: Edge With Your String Trimmer At A Slow But Steady Pace

Don’t get in a rush as you do this, especially in the beginning when you are learning. You want to move slowly but deliberately along the edge line, careful to stay on your intended path. You can absolutely maul your yard’s edge line if you try to go too fast. Remember, slow and steady wins the race.

Walk slowly as you edge with a weed whacker to ensure precise edges.

Why Use The Shoulder-Mount Approach

It’s possible to simply rotate the shaft and edge by holding the trimmer in much the same fashion as you would when weed-eating. The problem is that this technique can result in more back strain.

I found that my back was always aching when trying to edge in this manner. By holding the trimmer next to my shoulder I can rest the shaft on my arm and significantly reduce back strain.

Additionally, as I stated earlier, simply rotating the weed eater’s head will not give you a true 90-degree angle for edging. You need to raise the back end of the trimmer to get this angle.

Tips For Best Practices When Edging Using A String Trimmer

Flying Debris

As a rule, you are going to want to be extra mindful of nearby cars, windows, and people since edging with a string trimmer does not provide the same level of debris control as it does when using it for trimming.

Always wear safety glasses and be mindful of flying debris when edging with a weed eater.

You have to remember that the plastic debris guard is turned up while edging. While this may help to prevent some debris from flying directly up, it sure doesn’t stop it from shooting out to the side.

Since we decided on rock for our flower bed (we considered pine straw but you may want to read this article if you are considering using pine straw as mulch.

The point is, small rocks and sticks can act like projectiles as they are thrown away by the string. Be mindful of this. Wear eye protection and always be aware of the direction that the debris is being thrown.

Straight Lines Take Patience And Practice

If you find yourself frustrated with the results you are getting, remember that this is a new technique for you and that it will take some time to get good at it. If you stick with it you will be surprised how quickly you can master straight edging lines. It may never overshadow the results of a truly dedicated edger, but it will still give you impressive results with a little practice.

Can I Taper My Edges With This Technique?

If you prefer to taper the edges instead of having a 90-degree angle, you can simply rotate the shaft slightly so that the trimmer cuts at roughly a 45-degree angle. This is very easy to do and might be a better solution for you depending on your situation.

Is An Electric Or Gas Powered String Trimmer Better For Edging?

The results will be the same but electric trimmers do generally offer a weight advantage over gas-powered models. For example, the gas-powered Husqvarna 129C weighs 10 pounds. Compare that to the WORX WG163 20V battery-powered trimmer that weighs just 5.3 pounds.

At the same time, it depends on your physical condition and comfort level. The Stihl KombiSystem that I use weighs around 12 pounds with the trimmer attachment. My 14-year-old son and I use it just fine for edging. If you feel that the weight may be an issue, however, read below to ascertain whether you should use your string trimmer to edge or just buy a dedicated lawn edge tool.

Note: There is also a significant noise difference between gas and battery trimmers. As for technique, however, the shoulder-mount approach can work for either model so long as the shaft length allows for it.

Should You Use A String Trimmer Or Just Buy An Edger?

As I said at the onset, this technique works but it will not give you the level of precision that you will get from an actual edger. There are several factors that you need to consider if you plan to edge with a string trimmer.

Edge Lines Are Not As Accurate

Lines are not as accurate when using a string trimmer for edging.

I explained earlier that straight lines take practice but you should be realistic in your expectations. There is no edge line as clean and distinct as the cut from a dedicated lawn edge tool.

I have watched lawn care pros using the should-mount edging technique with string trimmers and they can get impressive results. But there are two important points to note:

  1. they do this for a living, and
  2. as good as those cuts are, it still is not as perfect as an edger would be.

What is important here is that you manage your expectations and remember that you will get better at it with time but it may never quite reach that precision-groomed look that a true lawn edge tool gives.

Edge Tools Are A Better Choice Ergonomically

Shoulder-mounting a string trimmer to use it as an edger does relief a lot of the back pain but you are still using the tool it a manner that it was not designed for. As a result, it is not as ergonomically friendly as just using an actual lawn edge tool. Edgers are designed to be operated in that orientation and so they are generally more comfortable to use for longer periods.

I get by just fine using my weed eater as an edger but I recognize the benefit of having the right tool for the job. As a result, I’ve been on the search for a solid battery-powered edger. I’ve even considered going the dual-purpose route with the WORX WG163 which is both a trimmer and an edger and is powered by a 20V lithium-ion battery.

What I do not recommend unless you have very specific circumstances is a corded edger (or trimmer for that matter). I actually own a Black and Decker corded Edger and it sits in my garage collecting dust because it is just too much of a hassle to use. Save yourself the frustration and go with a battery-powered model if you choose to purchase a separate edge tool.


You can absolutely edge with a string trimmer. It takes some practice and it’ll never truly match the precision of a dedicated edge tool but it can be done.

Take your time, perfect your technique, and don’t beat yourself up over a few mauled areas as you are learning. The more you do it the better you will get at it. And that holds true for pretty much anything in life.

You may have noticed that I use a Stihl trimmer. I’ve used their powered yard tools for years. If you are interested in learning if the performance and reliability of this brand warrant the cost, read my article titled Are Stihl Trimmers Worth The Money? Cost Vs. Benefit Review.

If you already own a Stihl trimmer, make sure you understand How To Grease The Gearbox.

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