Many grass trimmers cut using a string-like line that rotates at speed, strimming grass and stems.
However, unlike the other cutting method – plastic blades – the line system seems to cause lots of frustration with users. In fact, the most common complaint about grass trimmers is how often the line breaks.
In our tests we deliberately hit the grass trimmer's line on a metal edge to see how often the trimmer loses it. This way, we can find those grass trimmers that will quickly spool out more line and those that will have you fiddling around for ages to repair it.
Head straight to our best grass trimmers reviews.
Video: how to avoid line-feed problems
Top tips to avoid grass trimmer line-feed problems
- Keep the head of your trimmer clean - dirt build-up can clog up the line-feed mechanism.
- Keep plenty of line on the trimmer head - don't worry that your line is too long. The trimmer head has a blade that will cut off any excess so it's the optimum length.
- Wrap the line carefully - if you don't, it could easily lead to a jam and the line being lost.
- Look for a trimmer with thicker line - if it looks twisted, like a liquorice string, then it's usually a more heavy-duty line that's less likely to break. Look for line that's at least 1.2mm thick.
- Avoid hitting the line on fences and metal edging - this will break off chunks of line and the trimmer might not push out new line quickly enough.
- Use a trimmer with one line - a trimmer with one line is generally easier to thread than a trimmer with two.
- Take breaks - if you're trimming for a long period of time, the spool might get hot, causing the line to stick together and not feed through properly.
- Use the manual-release button - if the trimmer isn't pushing out more line automatically, it could be that the cord is slightly tangled up inside; the manual-release button means you can pull more line out past the problem.
You might prefer a trimmer that uses a blade instead of a line – jump straight to our grass trimmer reviews to find one.
How to cut lawn edges
- Start by adjusting your grass trimmer so you can comfortably hold and control it when cutting a vertical edge.
- Rotate the head to cut vertically and adjust the shaft length if necessary, as well as the position of the handles.
- Stand so that you can clearly see where you're cutting.
- Try to look along the length of the lawn edge to avoid cutting a jagged line.
- Cut slowly, checking regularly that you're cutting straight.
How to cut around trees and shrubs
Some grass trimmers have a plant guard, which is a wire hoop that projects in front of the grass trimmers. Remember to keep this up against the tree or bush, and be aware that if you swipe sideways you will cut into the bark.
It's very easy to accidentally catch the base of trees and shrubs with your grass trimmer, which rips the bark, letting disease into the plant. In the worst cases it's possible to kill a tree if the bark is cut right around the trunk.
- Use your guard to protect the tree by placing it against the trunk. Then step backwards, pulling the grass trimmer around the base of the tree.
- Keep the guard between the trimmer head and the tree.
Want to replace your grass trimmer? See our top five grass trimmers and lawn edgers.
How to cut long grass and weeds
Back in the day, this job would have been done using a scythe, so think of your grass trimmer in much the same way.
- Swing it from side to side, cutting in one direction only. This will push all the debris in the same direction, making it easier to see where you have cut, and to clear up afterwards.
- If you've got a lot of trimming to do, it's easy to put stresses and strains on your body, so avoid this by swinging the grass trimmer only as far as is comfortable.
- Step forward between each swing to move in a straight line.
- Then turn around and walk back in the opposite direction to complete the next line.
Remember to feed out plenty of line when you're doing this. The line will break regularly and there's a risk that you will lose it if you don't feed out more regularly. You will also work more efficiently by using the maximum cutting area.
Head to our expert buying guide to find the useful features that will help with trimming jobs.