How we test hedge trimmers
By Adele Dyer
Which? tests hedge trimmers on deciduous, evergreen and conifer hedges to find the best ones for keeping your garden looking neat.
Watch the video above to find out what we look for in a hedge trimmer and what makes our Best Buy models the quickest and easiest to use.
Hedge trimmers take the hard work out of keeping your hedges looking neat, and a well-cut hedge will make the whole garden look better. We carry out independent, scientific tests designed to discover how well hedge trimmers cope with challenging hedges and whether they leave them looking crisp and neat or chewed and ragged.
Our reviews answer the most crucial questions about hedge trimmers:
- How well does the hedge trimmer cut a variety of hedge types?
- Will it cut neatly or leave the hedge looking ragged?
- How quickly will the hedge trimmer cut?
- Will the hedge trimmer be easy to use?
- How much hedge can I cut with a cordless hedge trimmer?
- How safe is the hedge trimmer?
- Should I buy it?
Find out which models are the best at cutting all types of hedges in our hedge trimmer reviews.
How well does the hedge trimmer cut a variety of hedge types?
There are many shrubs that can be cut to form a hedge. Some, such as cherry laurel, have tough stems and leathery leaves. Others, such as privet, have thin, whippy stems and soft leaves. A good hedge trimmer should be able to cut through all types of growth, and we've developed our tests so that we now cut the most common types of hedge.
Over the past few years we've asked more of the hedge trimmers we test. In 2012, we cut only conifer hedges. In 2013, we added deciduous hedges, and in 2015, we also cut laurel hedges. The deciduous hedges in 2013 were blackthorn and hawthorn, while we swapped to privet in 2015, as this is such a widely grown hedge.
We added these hedges as we know you have these in your gardens and also because each hedge presents a different challenge for the hedge trimmer.
- Conifer hedges have whippy growth that can be stripped by poor hedge trimmers.
- Privet can be hard to cut with a smooth, even finish if the hedge trimmer is not fast and sharp.
- Laurel hedges have thick, waxy leaves and thicker stems that some hedge trimmers find hard to cut and leave a ‘chewed’ look.
Our three testers each cut at least 10m2 of each hedge type with each hedge trimmer to see how well they cut, how quickly they cut and how easy they are to use.
Will it cut neatly or leave the hedge looking ragged?
Not all hedge trimmers leave a neat finish. Some don't make a clean cut but rip through stems, leaving long 'tails' that make the whole hedge look untidy. Some don't cut neatly through leaves, but chew them up, again leading to messy-looking hedges.
Ragged cuts are not only untidy, they are unhealthy, too. Every cut can potentially let in disease and the larger and more ragged the cut surface, the greater the area where disease can find a way into the plant.
We look for hedge trimmers that cut cleanly through stems and branches, and our three experienced gardeners rate the quality of the finish.
How quickly will the hedge trimmer cut?
Our testers cut at least 10m2 of conifer, deciduous and evergreen hedges and time how long it takes to cut this amount of hedge.
The times are then averaged to make sure the time taken is representative of each hedge trimmer's performance and isn't affected by the user cutting through a particularly tough or gappy section of hedge.
How easy is the hedge trimmer to use?
Three testers assess each hedge trimmer for ease of use, taking into account how easy they would be for an older or less able gardener to operate.
They rated the machines on 18 criteria, including how easy they are to carry around, how comfortable the handles and switches are, how simple they are to use for vertical or horizontal cutting and whether noise, vibration, weight or balance are a problem.
All our hedge trimmer reviews include all their scores for performance and ease of use.
How much hedge can I cut with a cordless hedge trimmer?
Battery technology is improving rapidly and cordless hedge trimmers save the hassle of trailing leads on electric models and the weight and noise of a petrol hedge trimmer.
We cut the same three hedge types as with electric and petrol models, but rather than stopping after 10m2, we carry on until the battery has been exhausted. We note how many minutes this is and calculate how many metres of hedge we've cut in this time, and how well the trimmers have cut.We rate how easy the battery is to remove and refit, and time how long it takes for the battery to recharge.
How safe is the hedge trimmer?
We check hedge trimmers for electrical and mechanical safety. They should be designed in such a way that it's impossible to injure yourself in normal use. Features we look for include:
- Two separate switches so you have to keep both hands on the machine.
- The blades should stop the instant you release one of the switches, so touching a still-moving blade is impossible.
- The blade should have blade extensions – fixed teeth that extend well beyond the cutting teeth, so you can’t do serious damage if you accidentally brush the trimmer against your leg.
Over the 30 years we’ve been testing hedge trimmers, safety features have improved considerably. In the early days we campaigned to improve safety features and these have now been incorporated into international standards and adopted by all manufacturers.
Should I buy it?
Each of these assessments make up part of the overall test score, which is a percentage figure we award to each hedge trimmer. Some assessments are more important than others and so carry different weights. As electric, cordless and petrol hedge trimmers have different strengths and weaknesses, we adjust our test weightings accordingly.
Electric and petrol hedge trimmers
- 50% cutting tests
- 50% ease of use
Cordless hedge trimmers
- 40% cutting tests
- 40% ease of use
- 20% battery life
Electric hedge trimmers have to score over 74% or over to be awarded a Best Buy. Petrol hedge trimmers must score over 76% and cordless hedge trimmers must score over 80% to be a Best Buy.