Before putting the lawn mower away, clean it thoroughly and cover the mowing unit with a thin film of oil. First remove dried-on grass residue with a wire brush or a steam jet cleaner. Minor dirt can be cleaned off with a strong jet of water from the garden hose.
When mowing with petrol engines, allow the tank and the fuel line to run dry before putting away over winter. If the petrol tank is not completely empty, it is best to leave the engine running until it stops by itself. On motorised equipment, always disconnect the spark plug connector from the spark plug. On battery-operated mowers, remove the battery. With electric mowers, check whether the cable is still undamaged.
Winter is the best time to have the mower maintained professionally: oil change, air filter and spark plug replacement but also sharpening of blades are then often offered more cheaply by lawn mower dealers or specialist companies.