How to Clean and Store Your Lawn Mower for Winter

There's a particular kind of gardener's dread that arrives on the first warm Saturday of April. You wheel the mower out of the shed after five or six months of hibernation, give the cord a hopeful yank (or press the start button, or slot the battery home) and… nothing. A splutter, a wheeze, a cloud of blue smoke, or simply dead silence. And then comes the sinking realisation that the rest of your weekend is now going to be spent kneeling on a cold patch of concrete with a spark plug spanner and a rising temper.

I've been there more times than I'd care to admit. And here's the thing I've learned the hard way: nearly every one of those spring resurrection dramas could have been avoided with about an hour of care back in autumn. Proper winterisation isn't glamorous, and it certainly isn't the sort of task anyone leaps out of bed to tackle. But it's the single most valuable hour you can spend on your machine all year. Do it well, and a decent mower will keep running reliably for years — if not decades.

In this guide I'm going to walk you through the entire process, from the safety steps you absolutely must not skip, through the final clean, fuel and battery management, blade sharpening and a handful of extra maintenance jobs that petrol owners in particular will want to know about. Whether you've got a chugging petrol machine, a corded electric or one of the increasingly popular cordless battery models, there's a section here for you. Let's get your mower tucked up properly for the cold months.

Why Winterising Actually Matters

Before we get our hands dirty, it's worth understanding why all this fuss is necessary. A lawn mower is, after all, a fairly robust bit of kit. Surely it can just sit in the shed until spring?

Well, no — and the reasons come down to three quiet enemies that go to work the moment you stop using the machine: moisture, fuel degradation and neglect. Over a growing season that can easily stretch six months or longer, your mower accumulates a surprising amount of caked-on grass, dirt and general muck. Left to sit through a damp British winter, that debris traps moisture against the metal, and moisture against metal means one thing — rust and corrosion. The deck, the blade and the internal components all suffer.

For petrol mowers there's a second, sneakier problem. Modern petrol contains ethanol, which is hygroscopic — a fancy way of saying it attracts and absorbs water from the air. Leave fuel sitting in the tank all winter and condensation combines with that ethanol to produce a gummy, corrosive mess that clogs fuel lines and eats away at engine internals. Come spring, that's precisely why the engine won't fire.

And then there's the blade. A mower blade dulls gradually over a season of chopping through turf, and if you put it away dull, you'll pull it out dull. Starting the new growing season with a blunt blade is genuinely bad for your lawn — but more on that later.

The upshot is that winterisation is really a form of insurance. You invest roughly an hour of your time in autumn, and in return you dramatically reduce the odds of a frustrating, expensive or lawn-damaging start to the next season. Given that proper care can keep a machine running for years and often decades, that's about as good a return on effort as you'll find anywhere in the garden.

Safety First: The Non-Negotiable Starting Point

I want to be absolutely clear about this, because it's the one part of the process where cutting corners can genuinely hurt you. Before you touch any part of the machine for cleaning or maintenance — before you tip it on its side, before you go anywhere near the blade — you must render it incapable of starting. Every reputable source agrees on this, without exception.

The exact step depends on what kind of mower you own, so let me break it down clearly.

Once your machine is safely disabled, you can proceed with confidence. I like to physically set the spark plug cap or the battery to one side of my workspace, well away from the mower, as a visual reminder that the job isn't finished until it goes back. It's a small habit that's saved me from a few careless moments over the years.

Step One: The All-Important Final Clean

Every single guide worth its salt treats cleaning as step one, and for good reason. Ideally you'll give the mower an especially thorough clean immediately after the last cut of the year — that's the trigger point for beginning the whole winterisation routine. Cleaning while things are relatively fresh is far easier than tackling debris that's baked on and dried solid over weeks.

Your enemy here is the accumulated grass residue that adheres to the mower housing and, in particular, cakes underneath the deck. Left in place all winter, that damp organic matter holds moisture against the metal and drives rust and corrosion. So the goal is simple: get it all off.

Tackling the Deck and Housing

For the underside of the deck — where the worst of the buildup lives — a garden hose or, better still, a pressure washer makes short work of blasting away grass clippings and dirt. For dried-on, stubborn clippings that won't budge under water alone, reach for a paint scraper or a stiff bristled brush and work them loose mechanically.

On petrol mowers specifically, pay close attention to two areas that people routinely overlook: the cooling fins and the exhaust area. Grass residue trapped in the cooling fins can cause the engine to run hot next season, and debris around the exhaust is both a corrosion risk and, potentially, a fire hazard. A brush or a wooden scraper is ideal for teasing residue out of these tighter spots without scratching or damaging components.

Let everything dry thoroughly before you move on. This is a point people often rush, but putting a wet mower away and then applying protective lubricant over damp metal rather defeats the purpose. If you've used a hose or pressure washer, give the machine time to dry off completely — ideally leave it out in a breezy, dry spot for a while — before the next steps. A mower that goes into storage bone-dry is one that comes out of storage rust-free.

Step Two: Managing Fuel and Power Sources

This is the step that varies most dramatically depending on what type of mower you own, and it's also the step that most directly determines whether your machine starts next spring. Let's take each type in turn.

Petrol Mowers: The Fuel Question

As I touched on earlier, leaving petrol in the tank all winter is asking for trouble. Water from condensation combines with the ethanol in modern fuel, and the result is clogged fuel lines and engine corrosion — the classic recipe for a mower that refuses to start in April. So you've got to deal with the fuel, and the right approach depends on where you're storing the machine.

The distinction matters. If your mower lives in a detached garage or a shed, well away from the house, a good-quality fuel stabiliser is a perfectly sensible choice — you add it to the tank and then run the engine for a couple of minutes to make sure the treated fuel circulates through the carburettor and coats the fuel system. That way everything is protected and ready to go come spring.

But if you're storing the mower in an attached garage or a basement — anywhere connected to your living space — the advice shifts firmly towards draining the tank completely. Stored petrol is a genuine fire hazard, and you don't want that risk sitting next to your home. Run the engine until the tank runs dry so there's no fuel left to worry about.

Cordless / Battery Mowers: Look After the Battery

Battery mowers make this step delightfully simple. You've already removed the battery as part of the safety routine, so now you just need to store it correctly. The key point is that cold temperatures can shorten a battery's lifespan, so you want to bring it indoors for the winter and keep it somewhere that won't freeze.

Don't leave the battery clipped into a mower that's sitting in an unheated shed or garage where temperatures plummet. Instead, take it into the house — a cupboard, a utility room, anywhere reasonably temperate — and let it wait out the cold in comfort. Your battery will thank you with a longer service life and better capacity retention.

Electric (Corded) Mowers: Keep It Simple

Corded electric mowers are the most straightforward of the lot on this front. With no fuel and no battery to manage, the main job is simply to disconnect the power cord before any work, which you've already done. Beyond that, focus your attention on the cleaning and blade steps, coil the cord neatly to avoid kinks and damage, and you're most of the way there.

It's worth pausing on this comparison, because it tells a genuine story. The sheer number of extra steps required to winterise a petrol mower — fuel management, spark plugs, oil, air filters and more — really does underscore the fact that battery-powered mowers are the low-maintenance way to go. If you're weighing up a new machine and dread the annual faff, that's a point worth bearing in mind.

Step Three: Sharpen That Blade

Of all the winterisation steps, this is the one people most often skip — and it's a real shame, because a sharp blade is one of the biggest single factors in a healthy, good-looking lawn. Whatever you do, do not resume mowing in spring with a dull blade.

Here's why it matters so much. A dull blade doesn't cut the grass cleanly — it tears at the turf-grass instead. Torn grass leaves ragged, frayed ends that make your lawn look scruffy no matter how neatly you've mowed the lines. Worse, those tears create open wounds in each blade of grass, and that makes the whole lawn far more susceptible to disease. So a blunt blade isn't just cosmetic; it's actively bad for the long-term health of your turf.

The recommended approach is to remove the blade and take it to a lawn mower repair shop for sharpening. Professional sharpening gets the angle and balance right in a way that's genuinely difficult to match at home, and it's usually inexpensive. Winter is the perfect time to do this, because you're not in a rush to get back out mowing — the blade can sit at the shop for a few days without inconveniencing anyone.

Remember, of course, that the blade sits right at the business end of the machine, so all your earlier safety precautions apply doubly here. The spark plug must be disconnected (or the battery removed) before you go anywhere near the blade with a spanner. Take your time, wear gloves, and treat the edge with respect even when it's dull.

Extra Maintenance for Petrol Mowers

If you own a petrol machine, there are a few additional maintenance jobs that are well worth folding into your winterisation routine. These don't apply to electric or battery mowers — which, again, is rather the point about battery models being the lower-maintenance option — but for petrol owners they can make a meaningful difference to engine longevity and reliable starting.

Oil Change

Periodic oil changes will extend the life of your engine, and winter storage is a natural moment to tackle one. That said, not all petrol mowers require oil changes — some smaller or simpler engines don't — so the golden rule here is to check the user's manual for your specific model before proceeding. If your manual calls for periodic oil changes, doing one before storage means fresh, clean oil is protecting your engine internals over the winter rather than old, contaminated oil sitting there degrading.

Spark Plug Inspection

Replacing the spark plug used to be a standard part of the annual maintenance checklist, but times have changed. Modern spark plugs typically last a few years or longer, so you no longer need to swap yours out every single season. Instead, do a visual inspection before winter storage and let the plug's condition guide you.

If the plug looks clean, sound and free of these problems, you can simply refit it (once you're finished with all your other work, of course) and carry on. If it shows any of the warning signs above, replacing it is cheap and easy, and it's one less thing to worry about come spring.

Air Filter

The air filter plays a crucial protective role — it keeps dust, grass particles and debris out of the engine, guarding those precious internals from abrasive contaminants. A clogged or filthy air filter forces the engine to work harder and can affect performance, so winter storage is a sensible time to check it over. If yours is caked in dirt, cleaning or replacing it as your manual directs will help ensure the engine breathes freely when you fire it up again in spring.

Step Four: Choosing the Right Storage Location

You've cleaned the machine, sorted the fuel or battery, sharpened the blade and run through any extra maintenance. The final piece of the puzzle is deciding where the mower will actually spend the winter, because the storage location influences several of the earlier decisions — most notably how you handle the fuel.

As we covered in the fuel section, the choice between a detached and an attached space is the key one. A detached garage or shed lets you take the fuel-stabiliser route, keeping the tank topped up and treated. An attached garage or basement, on the other hand, calls for draining the tank entirely because of the fire hazard that stored petrol poses so close to your home. It's a genuine safety consideration, not just a matter of convenience, so make the decision deliberately.

For battery units, the storage question is really about the battery pack rather than the mower body. The machine itself can happily sit in the shed or garage, but the battery should be stored indoors in non-freezing conditions, since cold temperatures shorten its lifespan. So you might store the mower in the shed and the battery on a shelf in the utility room — two different homes for two different components.

Whatever space you choose, aim for somewhere dry and reasonably protected from the worst of the damp. Moisture, remember, is the underlying enemy in almost every winter storage problem. A dry, sheltered spot combined with a properly cleaned and lubricated machine is the winning combination that sees your mower emerge in spring exactly as you left it.

A Realistic Look: Petrol vs Electric vs Battery for Winter Care

Having taken you through the whole process, it's worth stepping back to compare how the three main mower types actually stack up when it comes to seasonal maintenance. This isn't about which cuts grass best — it's specifically about the winterising burden, because that's a real, recurring cost of ownership that people rarely factor in when buying.

The pattern practically leaps off the page. Petrol mowers demand the full checklist: fuel, oil, plugs, filters, the lot. Corded and cordless machines share just the universal jobs — cleaning and blade care — with the battery model adding only the simple task of storing its pack somewhere warm. If the annual maintenance ritual fills you with dread, this table alone makes a compelling case for going electric or cordless next time you're in the market.

That's not to say petrol mowers don't have their place — they're powerful, cordless-freedom machines that suit larger lawns beautifully, and plenty of gardeners genuinely enjoy the ritual of engine maintenance. But go in with your eyes open about what winter (and spring, and general upkeep) will ask of you.

Rating the Winterisation Payoff

So, is an hour of end-of-season care actually worth it? Having done this every year for longer than I'd like to count, I can offer a fairly confident verdict on the process itself. Here's how I'd score the winterisation routine across the factors that matter to most gardeners.

The reliability boost and longevity payoff score highest because those are where winterisation truly earns its keep — the difference between a mower that starts first pull in April and one that needs an expensive trip to the repair shop, and the difference between a machine that lasts a handful of years and one that soldiers on for decades. The only marks I've held back are for skill and time, and even those are minor: the process is well within any competent DIYer's reach and fits comfortably into a single autumn hour.

Frequently Asked Questions

Who This Routine Is For

And that, honestly, is the whole secret. There's no dark art to any of this — just a handful of sensible steps done in the right order at the right time. Tackle it once properly this autumn and you'll never dread that first warm Saturday of spring again. Your mower will be ready, your lawn will thank you, and you'll have the rest of the weekend to enjoy the garden rather than fighting with the shed's least cooperative resident.