A lawn mower works hard for half the year and then sits still for the other half, and both halves need managing. The maintenance splits neatly across the seasons, so organising it that way means each job happens at the point it does the most good.
Spring: Getting It Ready
The first start of the year is where summer’s reliability is decided.
- Fuel. If the mower was stored with untreated gasoline, drain it and refill with fresh fuel. Gasoline containing ethanol degrades in about a month, and stale fuel left in the carburetor over winter is the leading cause of a mower that won’t start in April.
- Oil. Change the engine oil and filter where one is fitted. Four-stroke mower engines typically take SAE 30 or 10W-30, and the specification is in your manual.
- Spark plug. Replace it annually, gapped to specification. It’s a few dollars and it makes a noticeable difference to starting.
- Air filter. Clean or replace, depending on whether yours is foam or paper. Paper elements get replaced, foam elements wash, dry fully, and take a light coat of oil.
- Blade. Sharpen or replace it now. A sharp blade cuts grass cleanly, and a dull one tears it, which leaves brown, ragged tips and makes the lawn more vulnerable to disease. Balance the blade after sharpening so the mower doesn’t vibrate, and torque the blade bolt to the figure in your manual.
- Battery. On electric-start and battery models, charge and test before you need it.
Summer: Keeping It Running
In-season maintenance is mostly about the things that accumulate during use:
- After every few mows, scrape the grass buildup from the underside of the deck. Packed clippings restrict airflow, which spoils the cut quality and bagging performance, and they hold moisture against the metal, which rusts the deck from below. Always disconnect the spark plug lead before putting your hands anywhere near the blade.
- Check the oil level at every few uses, and top off as needed.
- Watch the air filter, since summer mowing in dry conditions loads a filter quickly.
- Sharpen the blade again mid-season if you mow a large area. Most people sharpen once a year and would get better results from twice.
- Check tire pressures on ride-on mowers, because uneven pressures produce an uneven cut.
- Keep the cooling fins clear on air-cooled engines, since clippings packed around the cylinder cause overheating.
Autumn: The Heaviest Work Of The Year
Fall leaves and damp, heavy grass put more strain on a mower than anything in summer. Keep the deck clean, because wet clippings stick far more readily. Raise the cutting height for the final cuts of the season, and if you’re mulching leaves, work in several passes so you’re not overloading the engine and blade in one go.
Watch for signs of strain: a bogging engine, a blade that stalls in thick material, or unusual vibration. All three mean stopping and checking before something breaks.
Winter: Storing It Properly
How a mower goes away decides how it comes back:
- Fuel. Two options, both acceptable. Either drain the tank completely and run the engine until the carburetor empties, or fill the tank with fresh gasoline treated with stabilizer and run the engine for several minutes to circulate treated fuel through the system. A half-full tank of untreated gas is the one thing to avoid.
- Oil. Change it before storage, since used oil carries acids and moisture that shouldn’t sit against internal components for months.
- Clean it thoroughly. Remove all grass from the deck, wash it, dry it, and treat any bare metal with a light coat of oil or rust preventative.
- Blade. Remove, sharpen, and refit, or store it off the machine. Doing the blade now means one less job in spring.
- Battery. Remove it, charge it, and store somewhere dry above freezing, ideally on a maintainer.
- Storage position. Store the mower upright in a dry place. Tipping a mower on its side can let oil into the cylinder or air filter, and your manual specifies which side is safe if you need to tip it for blade work.
Battery And Electric Mowers
These skip the fuel and spark side entirely, and they still need the rest. Keep the deck clean, sharpen the blade on the same schedule, clear the motor vents, and store lithium packs at partial charge somewhere above freezing. Corded models need a cord inspection for nicks and cuts before each season.
Robot Mowers
Clean the blade disc and chassis regularly, check the small blades for wear and replace them on the manufacturer’s schedule, keep the wheels and sensors clear, and bring the unit and its charging station indoors for winter where the manual advises it.
Find The Manual For Your Machine
Blade bolt torque, oil capacity, plug gap, belt part numbers, and deck adjustment procedures all differ by make and model, and small equipment documentation tends to disappear long before the machine does. At emanuals, you get garden machinery workshop manuals for mowers, trimmers, blowers, and everything else in the shed, held in a library of over 5 million OEM titles with every PDF yours to keep. Get a membership and keep the factory data alongside the machine.
FAQs
How often should I sharpen my lawn mower blade?
At least once a year, and twice if you mow a large area or cut frequently. A sharp blade slices the grass cleanly, while a dull one tears it, leaving brown tips and making the lawn more prone to disease.
What oil does a lawn mower take?
Most four-stroke mower engines specify SAE 30 in warm conditions or 10W-30 across a wider temperature range, but check your manual, since capacities and grades vary. Two-stroke engines take a gasoline and oil mix at the ratio printed on the machine.
Should I drain the fuel before winter storage?
Either drain the tank and run the carburetor dry, or fill it with fresh fuel treated with stabilizer and run the engine to circulate it. Leaving a partly full tank of untreated gasoline over winter is what causes most spring starting problems.
Can I tip my lawn mower on its side to clean the deck?
Only in the direction your manual specifies, which is usually with the air filter and carburetor facing upward. Tipping the wrong way lets oil flow into the cylinder or air filter, which causes smoking and hard starting.
Why won’t my mower start in spring?
Stale fuel is the most common cause, followed by a fouled spark plug and a clogged air filter. Drain the old gasoline, fit a fresh plug, check the filter, and the large majority of spring no-starts resolve at that point.