How to Clean a Lawn Mower After Use: A Ten Minute Routine

The best time to clean a mower is the moment you finish cutting, while the clippings under the deck are still damp and lift off with a scraper. Isolate the machine first, then clear the deck, empty the grass box, brush out the vents and dry everything before it goes back in the shed. Ten minutes now saves you an hour of chipping off baked-on grass in a fortnight.

Isolate the mower before you touch the deck

This is the part people skip and it is the only part that can genuinely hurt you. A blade turns freely by hand, and on a petrol engine that turns the crankshaft, which can fire the plug and kick the blade round hard.

• Petrol: stop the engine, let it cool, then pull the spark plug cap off and tuck it away from the plug.
• Cordless: remove the battery pack completely. Switching it off is not enough.
• Mains electric: unplug at the socket, not just at the extension lead.

Wear a thick glove on the hand that goes near the blade. Even a blunt blade will open up a finger if it moves unexpectedly.

Step one: clear the top and the deck edges

Start above the deck while the machine is upright. Brush loose clippings off the top of the housing, out of the handle folds and away from the cooling slots. A stiff bench brush or an old paintbrush does most of it. On a petrol mower, keep grass out of the recoil starter housing and off the engine fins, where trapped debris causes overheating.

Step two: clean the underside

How you tip the mower matters more than what you clean it with.

Petrol mowers

Tip the mower so the spark plug points upwards and the air filter stays high. Tipping the other way lets oil run into the cylinder or soak the filter, and you get blue smoke and a rough-running engine next time. Some makers ask you to tip forwards only, so check the handbook. If the tank is nearly full, run it down first or petrol weeps out of the cap vent.

Cordless and electric mowers

With the battery out you can lay these on their side or tip them back freely. Keep the motor housing and vents pointing away from where you are scraping so debris does not drop in.

Now scrape. A plastic paint scraper or a wooden shim works and neither will gouge the housing. Work from the centre outwards and pay attention to the ring of packed grass around the blade boss and along the discharge chute. That layer strangles airflow under the deck and causes the poor lift, uneven finish and clumping most people blame on the blade.

Step three: the grass box, chute and filters

Empty the collector every time, even if it is half full, because damp clippings rot in a fabric box and clog the mesh. A blocked mesh is the usual reason a box stops filling properly. Rinse fabric boxes, shake them out and stand them open to dry. Check the chute and mulch plug too, since compacted grass in there ruins the next cut before you have gone ten metres.

On petrol mowers, tap the paper air filter out on a hard surface once the deck is done. If it looks grey rather than off-white, replace it. Foam pre-filters wash in warm soapy water, but never refit one while it is still wet.

Step four: look at the blade while you are down there

The mower is already tipped and isolated, so it costs nothing to run a gloved thumb along the cutting edge. Look for nicks, a rolled-over edge, or an edge that feels rounded rather than defined. Check the blade bolt is tight and that a hidden stone has not bent the blade, which shows up as vibration through the handles.

Step five: dry it, then protect it

Water is fine as a cleaning aid but it is the reason decks rust through. Once the deck is clear, wipe it dry rather than leaving it in a damp shed. On a steel deck, a light wipe of thin oil or silicone across the underside slows corrosion and makes the next clean easier, because clippings do not key into a slick surface.

Things worth avoiding

• Pressure washing the mower. It forces water past bearings, into the motor housing and behind wheel bushes, and strips the coating off the deck. It is the fastest way to turn a five year mower into a three year mower.
• Hosing a petrol engine. Water in the carburettor, ignition or air filter causes starting problems far more annoying than the grass you removed.
• Solvents and degreasers on plastic housings. Warm soapy water is enough.

How often is enough

A deck scrape and box empty after every cut is what keeps a mower healthy. Once a month in the growing season, add the air filter check, the blade inspection and a look at the wheels and height adjusters. Do the full version before winter storage, because a deck left with wet grass on it comes out in spring with holes in it.