Which grass trimmer brand to buy in 2021

The line feed malfunctioning is the most common fault you'll find on a grass trimmer, whether you own a corded, cordless or petrol model.

Otherwise, you'll likely find specific problems on the different types of trimmer, such as battery not holding charge on a cordless or the engine not starting or turning over on a petrol grass trimmer.

Knowing which brands develop the most faults, and how quickly, is vital when buying a new hedge trimmer. That’s why we asked 2,537 Which? members to tell us whether they're happy with their grass trimmers, or have experienced problems, in our unique reliability and customer satisfaction survey.

Our survey data takes into account the reported fault rates, the severity of these faults, and the speed with which they occurred. In our latest analysis, we've looked at the performance of the biggest grass trimmer manufacturers – including Bosch, Flymo, Ryobi and Stihl – and have calculated a reliability rating and customer score for each, so you know which brands to choose and which to avoid.

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Best vs worst grass trimmer brands compared

We’ve found huge differences between how satisfied owners are with their grass trimmers.

Pick a Best Buy grass trimmer if you're after a top performer that's also easy to use.

The most reliable grass trimmer brands

The table below summarises our latest reliability results. Brands are ranked by their customer score, which relates to whether their customers would recommend that brand. 

The higher the percentage score for reliability, the fewer the problems reported. 

In the table below, only logged-in members can view which brands are the most and least reliable, and which ones members are most satisfied with. If you're not yet a member, join Which? to get instant access.

Petrol vs corded and cordless electric grass trimmers

Table notes: The data in the tables below is based on a survey of 1,479 Which? members in January 2020. (-) Brands with insufficient sample sizes not included. Results from corded, cordless and petrol hedge trimmers combined. 

How long will my grass trimmer last?

We've found that on average, all types of grass trimmers last around the same amount of time: 7.4 years for petrol, 7.7 years for cordless and 7.8 years for corded electric.

This is based on the experiences of Which? members who told us how long they kept their previous appliance before they had to replace it, either because of a fault or because it wasn’t working as well as when they first bought it.

As you can see from the table above, there’s a big difference between how long the best and the worst hedge trimmer brands last.

Common grass trimmer problems

The line feed breaking is the most common problem across all three types. This is an annoying, rather than a devastating, issue and can be fixed on the spot.

Luckily, most of the top faults are also fixable, or at least won't result in the total breakdown of your trimmer.

Top three common corded grass trimmer faults

1. 65% - Line feed malfunctioned The line feed that's used to cut your grass can break or become jammed. You can usually fix it manually. 
2. 7% - Head failed to rotate This would make cutting vertically quite tricky, but probably won't spell the end of your trimmer.
3. 4% - Guard broke A plant guard stops you from accidentally cutting up your flowerbeds. You can some-times buy a spare if yours breaks.

Top three common cordless grass trimmer faults

1. 25% - Automatic line feed malfunctioned The line feed that's used to cut your grass can break or become jammed. You can usually fix it manually.
2. 24% - Blades broke Always wipe your grass trimmer blades with a rag and lubricant after use. It prevents rust and keeps the blades in good condition.
3. 10% - Battery would not hold charge Lithium-ion batteries always lose their ability to hold charge eventually. That's why you should always buy a grass trimmer with a replaceable battery.

Top three common petrol grass trimmer faults

1. 32% - Chain broke Keep your chain oiled and tighten it before use to keep it in good condition. If it does break you can usually buy a replacement.
2. 11% - Electrical failure This is a pretty major failure. You'll likely need to get it professionally repaired, or replace it.
3. 4% - Chain guard broke It's best to take this to a professional to avoid throwing out the whole chainsaw.

Which grass trimmer brand stays fault-free for longest?

The graph above shows how the brand that stays fault-free for longest compares with the worst brand, and the overall average across all three types of grass trimmer. Which? members can see how brands compare for faults over a six-year period (or five years for cordless grass trimmers) in the table below.

How we measure faults and reliability in grass trimmers

Our data takes into account minor, major and catastrophic faults:

• Minor faults don't affect the grass trimmer's performance significantly, or only occur occasionally with minimal impact. The issue may be irritating or annoying, but isn't frequently problematic, and you can easily work around it. For example, the line feed breaking
• Major faults have a noticeable effect on the grass trimmer's performance. They affect how you use it, and can be problematic. For example, the line head not rotating.
• Catastrophic faults will render the hedge trimmer unusable, with the fault needing to be repaired or parts replaced before you can use it again. For example, an electric fault meaning it won't turn on.

Grass trimmer brands verdicts

Log in or join Which? to get instant access to our lawn mower brand verdicts.

We look at the brands in more detail, including number of Best Buys it’s received and the average score of its lawn mowers in our reviews.

Head to our hedge trimmer reviews

Know which hedge trimmer brand you want? Use the links to go straight to our reviews and find your ideal model:

• Black and Decker hedge trimmer reviews
• Bosch hedge trimmer reviews
• Flymo hedge trimmer reviews
• Qualcast hedge trimmer reviews
• Ryobi hedge trimmer reviews
• Stihl hedge trimmer reviews

How we calculate the best and worst brands

Which? has a wealth of information on the UK’s favourite garden-tool brands. Every two years, we ask Which? members to tell us about the garden products they own - from how likely they'd be to recommend a brand, to how reliable the products are once you get them home. This year, almost 5,000 members told us about more than 11,000 products. We calculate a brand's reliability and its customer score based on the results of our biennial survey.

Our reliability surveys, combined with our extensive lab tests, mean we can recommend the best grass trimmer you should buy.

This data is crucial for our testing, too. If a brand falls far below the category average, we take away the manufacturer's Best Buy recommendations and won’t recommend any of its products unless it shows a marked improvement in reliability.