How to Winterize a Lawn Mower for Winter Storage
To winterize a gas mower, add fuel stabilizer to a full tank and run the engine for 5 minutes, or run the tank completely dry, then disconnect the spark plug wire before you clean the deck, check the oil, and store it somewhere dry. For a battery mower, remove the battery, charge it to roughly 40 to 60 percent, and store it indoors above freezing. Do this after your last mow, usually in late October or November.
Stale fuel is the main reason mowers refuse to start in spring. Ethanol-blended gasoline starts breaking down in about 30 days and leaves varnish in the carburetor. Ten minutes of prep in fall saves a repair bill in April.
Safety first: a lawn mower is a dangerous machine even when it is off. Always read and follow your manufacturer's operator manual, which overrides any general advice here. Never work under the deck or near the blade without disconnecting the spark plug wire (gas) or removing the battery and safety key (electric). If you are unsure about any step, have a small-engine shop or dealer do the service.
Why winterizing matters
- Fuel goes bad. Untreated gas left in the tank and carburetor over winter gums up jets and fuel lines.
- Wet clippings cause rust. Grass packed under the deck holds moisture against the steel all winter.
- Batteries suffer in the cold. Lithium-ion packs lose capacity when stored fully charged, fully drained, or below freezing.
- Spring is the busiest season for repair shops. Mowers that sat with old fuel fill the queue, and waits can run weeks.
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- Read your operator manual's storage section first; follow it over any general checklist.
- Let the engine cool completely before touching the deck, muffler, or fuel system.
- Gas mowers: add stabilizer to fresh fuel and run 5 minutes, or run the tank dry outdoors.
- Disconnect and secure the spark plug wire, or remove the battery and safety key, before any cleaning.
- Wear cut-resistant gloves and eye protection when working anywhere near the blade.
- Scrape dried clippings off the deck with a plastic scraper; never use your hands near the blade edge.
- Check oil level and change it if the manual calls for an end-of-season change.
- Store in a dry shed or garage, away from furnaces, water heaters, or any open flame or spark source.
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Fuel stabilizer, a deck scraper, and a breathable cover handle most of the winter prep. We may earn a commission at no extra cost to you.
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Should you drain the gas or use stabilizer?
Either works if you do it fully. Many manufacturers recommend stabilizer in a full tank because it keeps the tank from rusting and the seals from drying out. Others recommend running the engine until it stalls so the carburetor bowl is empty. Check your manual and follow it. Do not siphon or pour gasoline indoors, and never drain fuel near a pilot light, cigarette, or running engine. Gasoline vapor is heavier than air and travels along the floor.
What about the blade?
A dull blade tears grass instead of cutting it, and late fall is a sensible time to get it sharpened or replaced. Blade removal is the most hazardous step in mower maintenance. The edge can cut you even when dull, the bolt is torqued tightly, and tipping a gas mower the wrong way can flood the air filter with oil or spill fuel. If your manual describes the procedure and you have the right tools, follow it exactly, including the specified tipping direction, a blade-holding block, and the torque value on reinstall. Otherwise, take the mower or blade to a dealer or small-engine shop. Many offer a fall tune-up that covers the blade, oil, plug, and filter for a flat fee.
How should you store a battery mower?
Remove the battery and keep it indoors where temperatures stay between about 40°F and 80°F. Most makers recommend storing lithium packs partially charged rather than full. Keep the charger unplugged, keep the pack away from metal objects that could short the terminals, and do not store a damaged or swollen battery; take it to a battery recycling drop-off instead.
Riding mowers and tractors
Riding mowers follow the same logic, plus a battery tender for the 12-volt starting battery and a check on tire pressure. Because of their weight, any deck removal or blade work on a rider is best left to a dealer unless your manual walks you through it and you have help.
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Cut-resistant gloves and safety glasses for any work near the deck. We may earn a commission at no extra cost to you.
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Zone and timing notes
In Zones 3 to 5 the last mow usually falls in late October to mid November, so winterize right after. In Zones 6 and 7 it often lands in November. In Zones 8 to 10, warm-season lawns go dormant or slow down, and many gardeners mow occasionally all winter; in that case use stabilized fuel in each tank rather than full storage prep.
Bottom line
Stabilize or drain the fuel, disconnect the plug or pull the battery, clean the deck, and store the mower dry. Follow your operator manual and hand off blade work to a shop if you have any doubt. A mower winterized in fall starts on the first pull in spring.
Related reading
- Lawn mowing best practices
- Winter lawn care by zone
- Leaf mulch with a mower
- Fall lawn care guide by zone
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