There are several opinions on how often a lawn mower should be cleaned. This is mostly a matter of personal preference, with some preferring to clean lawn mowers and other garden tools thoroughly after every use while others would rather not.

Even for those gardeners who wipe down and brush off the top surfaces of their petrol lawn mower, not everyone will turn their mower upside down and carefully clean off grass clippings and debris from the underside of the mower—the area known as the deck. This debate can be summarised in three parts:

  • Is it necessary to clean the mower deck and why?
  • How often a petrol mower should be cleaned
  • How it should be done

As part of this routine maintenance procedure, there are several additional steps you should follow before putting your petrol mower away at the end of year which we’ll detail in this guide.

Check out our related guide: How to Service a Petrol Lawn Mower

Your Lawn Mower Deck Should Be Cleaned

Even the best petrol lawnmowers need to be cleaned. The reason for cleaning the deck – the enclosed housing underneath the mower where the blade spins – is to maintain cutting performance. Cleaning this area will improve lawn mower performance by allowing blades of grass to stand upright as the cutting blade spins to cut them. A lawn mower deck that is heavily soiled with dried grass clippings may deflect blades of grass so they can’t be cut properly. In some cases, this dried grass can even prevent the rotation of the blade itself.

To improve cutting performance, you could also use this opportunity to replace or sharpen your lawn mower blade.

Keeping the bottom deck clean also helps reduce the spread of lawn diseases which can cause damage to your lawn and other planted areas of your garden. This is the case whether you own a hover lawn mower or a self propelled model.

Manual mowers are just as easy to clean. Simply remove any stuck grass from between the cutting blades by wiping them with a damp cloth.

Electric lawn mowers and cordless lawn mowers should also be cleaned at the same intervals and using the same methods.

Clean Your Petrol Mower Twice Each Season

There is no exact rule about how often to clean your mower deck, but it should be done at least twice each mowing season. It may need cleaning more often if you regularly mow long grass or wet grass as these conditions can lead to even greater grass build up.

It’s also a good idea to clean the deck of your mower before putting it away for the winter. Leaving grass to rot and on the bottom of the mower over winter will make your job harder when you next go to use it in the spring.

How to Clean the Deck on a Lawn Mower

To clean the deck on your lawn mower, follow these simple steps:

  1. Empty the fuel tank (or run the mower until the tank is empty) then disconnect the spark plug lead
  2. Stand the mower on its side
  3. Use a garden hose or pressure washer to spray the deck. This will loosen some of the debris and dried grass clippings
  4. Scrub off the rest of the debris using a brush, soap and hot water
  5. Rinse then dry the metal deck of your mower

We also recommend cleaning the wheels by pulling any grass out of the wheel casing and wiping them all down with a damp cloth.

Useful Tip: To reduce the build-up of grass clippings sticking to the underside of your mower, spray vegetable oil onto the deck after cleaning it.

End of Season Maintenance

When you’re finished with gardening at the end of autumn, empty the petrol tank by allowing the lawnmower to run until empty and leave it empty until spring. Old fuel can decay which can lead to a gummy sludge sitting in your fuel tank which could damage the engine or make it difficult to start.

If emptying the tank isn’t an option, we recommend using a fuel stabiliser instead. Add the fuel stabiliser to the tank and run the engine for a minute so the new mixture is sitting in the fuel lines and engine.  

Once complete, drain the old oil engine before refilling it with fresh oil.

Need help starting your petrol mower? Our “How to Start a Petrol Lawn Mower” guide will assist.

Final Verdict

This simple cleaning and maintenance procedure will ensure your petrol lawn mower is ready to use when you take it out of the garage or shed next spring.