How to sharpen your lawn mower blades and other maintenance tasks

Dreading the thought of a sputtering mower or a patchy lawn come springtime? 

Not to worry – we're here with some expert tips. Keeping your lawn mower in top shape is easier than you think, and it's necessary to ensure a smooth and efficient mow all season long. Dive in and discover the secrets to a healthy mower and a thriving lawn.

In the market for a new mower? Check out our lawn mower reviews for the very best models. 

How to sharpen lawn mower blades

For the best performance you’re going to want to keep your mower blades nice and sharp, and you should aim to sharpen your mower blades at least once every mowing season. A dull blade is a nightmare to cut with, and it can damage your lawn. If the blade isn’t sharp enough, it will tear at the grass rather than cut it, giving a patchy finish. 

Once you’ve finished mowing, take a look at your lawn. If it looks rough and uneven, that’s a good indication that your blades need sharpening.

If you're planning on sharpening your mower blades yourself, take extreme care – you'll need protective eyewear, earplugs and gloves. Make sure your mower is powered off before you proceed. If the blade is extremely damaged, it will need replacing entirely.

Using an angle grinder, work along the blade slowly. Your mower blade has a natural angle to it, so make sure to follow that with your angle grinder closely as you don't want to dramatically change the shape of the blade.

You also have the option of taking the blade to a repair or hardware shop.

Breathe new life into your outside spaces. Sign up for our Gardening newsletter – it's free monthly

25% off Which? Gardening

Pay £36.75 for the first year and get the garden you want for less

Get this offer

How to clear out the undercarriage

Every time you cut your lawn, your lawn mower’s undercarriage is going to become clogged and dirtied by grass cuttings and debris. This will negatively impact performance and can even cause the spread of lawn diseases. 

Ideally, you should clean your lawn mower after each session –  especially if you’re cutting wet grass – but failing that, try to clean it at least every month. Use a wire brush, damp cloth or air line to scrape and spray away any debris clinging to your lawn mower’s deck. 

Some petrol models even have a ‘washout port’, which a hose is plugged directly into to wash out debris, but we wouldn't recommend you use your garden hose on any electric mowers as you're then running the risk of water getting in to and damaging the electronic components.

If you tip your mower on its side to clean it, make sure you have the air filter on the top so that no oil leaks into it. 

Check out our guide on how and when to cut the grass to learn how to mow the perfect lawn. 

How to service a petrol mower

A garden machinery specialist should be able to service and repair your mower, especially petrol models, so always check before you discard a mower that seems to be broken. A lawn mower service will cover various components including spark plugs, air filters, blades and oil.

If you're servicing your petrol mower yourself, first consult your lawn mower’s manual. It may give an indication of how often to change the oil, so check there, but a good rule of thumb is to either change it at the start of each mowing season or after 50 hours of use – whichever comes first. Regular checks with a dipstick, just like you would on a car, will also ensure that you’ve used the right amount. 

And while you’re changing or checking the oil, check the air filter and spark plugs, too. These are both pretty easy to clean and ensure your mower can turn over and run, but you should also keep in mind that, like oil, they should be replaced annually to help your lawn mower work as efficiently as possible.

At the end of each mowing season, it's best to run the mower until it uses all the fuel. Fuel that has sat in the mower for an extended period – over winter, for example – can become stale and may prevent the mower from starting. Alternatively, you can use a fuel stabiliser to prevent the fuel from degrading.

How to service an electric mower

Cordless mowers quite literally live and die by their batteries, and it’s imperative that you take proper care of them. The lithium-ion battery that you’ll find inside your mower is sensitive to extremes of temperature, which will damage the cells or reduce the performance. It’s best to store the battery indoors – and keep it away from any blisteringly hot greenhouses or sheds. 

In the off-season, you should make sure that you charge your battery up a few times, even though you’re not using it. If you allow the battery to deplete and stay at 0% charge, it may subsequently fail to hold any charge at all when you come to use it again. If the battery does permanently die, you should be able to use a replacement to get the mower up and running again, although you may be surprised at the price. 

In line with this, you should never buy a cordless mower with a battery that cannot be replaced or removed. 

As for corded mowers, our main piece of advice is to ensure that your power cord is in good working order. Any visible damage is a point of potential danger, and the mower should not be used until the cord is replaced or repaired in line with the safety instructions detailed in the user manual.

Unsure whether to go for an electric or petrol mower? Our guide to the best lawn mowers will help you find the perfect model for your garden. 

Replacement parts for lawn mowers

One thing to consider before buying any type of lawn mower is how easy it will be to get replacement parts if you encounter any issues.

You can expect most mowers to last a decent amount of time (at least seven years or more) but that doesn't mean you'll never need spare blades, springs, or perhaps a replacement mower belt.

Most major mower retailers, such as Bosch, Cobra, Flymo, Ryobi and Stihl, offer spare parts for their lawn mowers, either directly from their website or through a third-party seller.

It's always worth checking on the availability of spare parts before you commit to a purchase, as you don't want a minor fault to end up in you replacing your entire mower because you can't get hold of a certain part.

With cordless mowers specifically, you should check that it's possible to buy replacement batteries separately. We don't give Best Buys to models where the batteries can't be replaced, so will never recommend a mower that's destined to have an unusually short lifespan.

Check out our guide on which lawn mower brand to buy to find out about the most durable lawn mowers.