Grass trimmer reviews: Features explained
Types of grass trimmer
A grass trimmer works by spinning a nylon line or plastic blade incredibly fast so it slices through grass and weeds. There are three types – electric corded, electric cordless (battery-powered) and petrol.
In general, electric trimmers are best for tidying up and edging lawns but are less good on longer grass or rougher areas. They’re the cheapest type of trimmer and are a good choice for smaller gardens, but the cable can be a hassle.
Cordless trimmers are battery powered and work as well as corded on edging and cutting. They’re more flexible and ideal if you want to trim grass away from the house but don’t fancy using a petrol machine. The main drawback is they have limited battery power – don’t expect to trim for longer than 15 minutes on one charge. They’re also a lot pricier than corded models.
Petrol trimmers are noisy, powerful and make quick work of long grass and overgrown weedy areas. But achieving a neat finish on a lawn edge can be tricky as they can be awkward to use with precision. You can use them anywhere and there’s no battery to restrict usage time, so they’re ideal for larger gardens with overgrown areas to tackle. They’re also expensive.
Find out how we test grass trimmers
Grass trimmer features to look out for
If the head of the grass trimmer rotates you can change the angle of the head to cut horizontally or vertically without having to alter the handle position. So you can cut grass right up to the edge of a wall, then switch to vertical cutting to trim along the edge of a border in one easy motion.
Avoid stooping by choosing a trimmer with a telescopic shaft. You can adjust the length of the trimmer to suit your height, then adjust it again for anyone else who may use it.
Grass trimmer guard
If your trimmer comes with one of these you can use it to avoid damaging plants. It’s a wire guard that swings into place in front of the trimmer’s cutting head to safeguard against accidental cutting.
Most trimmers use nylon line that’s machine-spun really fast to slice through grass. This line is contained in a spool and as it wears down more line is fed out. There are different ways of releasing more line and it’s worth checking out before you buy.
The best trimmers feed it out automatically as required and are known as ‘line-fed’ models.
Others have a large button on the bottom of the head – tap this sharply on the ground and more line will be released. This is sometimes referred to as ‘bump feed’ – you bump the head to feed out more line.
A manual feed trimmer means you have to pull more line out yourself. These are less common than bump or line fed machines.
When the line runs out you can either buy replacement spools for £6-8, or buy bulk line and wind it yourself. Use line from the same manufacturer, or at least one of similar weight and thickness, or you’ll upset the feed mechanism.
Some grass trimmers now have a small replaceable plastic blade instead of a nylon line, rather like a small hover mower.
Replacement blades cost about £6 for a pack of 24 and are available from DIY stores, or by contacting the manufacturer for stockists.
Battery types for cordless models
The working life of batteries depends on a number of factors including usage, charge and discharge sequences. It's important to follow the manufacturer's instructions to get the most from your battery.
There are two main types of battery - NiCd and Lithium-Ion.
NiCd batteries are particularly affected by being intermittently topped up and should be left to fully discharge before being charged or it can shorten their life.
Lithium-Ion batteries are designed to deliver similar power with less weight. They also have little self-discharge and none of the memory effects associated with NiCd and so their life span can be expected to be considerably longer