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12 May 2022

5 mistakes you’re making with your grass trimmer

Plus expert tips on how to get the best from your grass trimmer when sprucing up your garden
Person using grass trimmer

A grass trimmer or grass strimmer (exactly the same tool) can be a speedy way to add the finishing touch to your garden. But there are common mistakes that can be made along the way, causing potential damage to the trimmer and making extra work for you.

We’ve rounded up five common mistakes y​​​​ou could be making and some advice on how to avoid them in the future.


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Hitting hard objects

It’s all too easy to accidentally catch the base of a tree, rockeries or walls and fences when you’re on a mission but this will likely cause the trimming line to break or, if it has a blade, blunting or breaking it.

If you do skim the base of a tree, you could also inadvertently allow bacteria to get in and cause some serious damage.

Feeding out more line can be trickier on some trimmers, which will slow you down. There’s three types of line feed:

  • Bump feed - where the grass trimmer is banged on the ground and feeds out new line. 
  • Automatic feed - where more line is fed out when the grass trimmer starts. 
  • Manual feed - where the user stops the grass trimmer and pulls out more line. 

Before starting the job, do a quick scan of where you’ll be using it and remove any stray rocks, movable pots or garden furniture to help prevent you bumping into anything. While you’re at it, also check for any animals that could be hiding. Hedgehogs can often fall victim to strimmers - so always check in the undergrowth. 

Some grass trimmers have a plant guard, which is a wire hoop that projects in front of the grass trimmer. Some require pulling out and putting into place so remember to do so and ensure you keep this up against the tree or bush, and be aware that if you swipe sideways you could still cut into the bark.

Learn how to avoid line-feed problems

Not knowing your spin direction

Understanding the direction of the spin is very important. If the line spins in an anti-clockwise direction, it will eject the cut grass from the left hand side and cuts better with the right side.

If the spin is anti-clockwise and you are moving along a fence or flowerbed, keep the right side of your body closer to where you are working. This will mean the head is positioned so that the grass is ejected to the left, otherwise it will be ejected onto the cut path you are trying to clear or straight onto a flower bed. This can then cause problems as the trimmer can get bogged down.

Take a look at our grass trimmer and strimmer reviews

Using your trimmer for too tough a job

Grass trimmer cutting weeds

For tough weeds such as brambles or for areas of brash, a brushcutter is a better option for you. This replaces the grass trimmer line head with one that has a multi-sided metal plate that spins at high speed. This is longer-lasting than a plastic blade or line but you must use these with extreme caution. Alternatively, employ a professional gardener to carry out this work for you. 

Not soaking your trimming line

To keep your line flexible and make it last longer, it should absorb moisture before use. Place it in water for a minimum of 24 hours before use, and if your spool hasn’t been used for an extended period, remove it from the cutting head and soak in water for two days before using it. It’s also worth having a spare mowing line to hand at all times, as they do require regular replacement.

Read our advice on how to avoid line-feed problems

Not cleaning it

To prolong the life of your grass trimmer, ensure you clean it after use. Not only will it last longer but a freshly cleaned trimmer will also perform better. Dirt and debris can build up in the trimmer head and clog up the line mechanism, which means it isn’t as efficient at spinning the cutting line. 

Before cleaning, ensure it’s switched off and unplugged from the mains, if it’s an electric corded trimmer. If it's a cordless model, remove the battery. Also ensure it’s had a chance to cool down after use. Wear protective gloves and, using a soft brush, brush away any grass from the trimmer’s outer casing.

Turn the trimmer over and remove any grass from under the guard and around the line feed or blades.

Before storing away your grass trimmer for the winter, give it a thorough clean and lightly spray the metal surfaces with a little WD-40, leave it on for 10 minutes before wiping dry.

Thinking of buying a grass trimmer? Go to our pick of the best grass trimmers with expert buying advice