There are are a few ways to approach repairing your damaged lawn, depending on what type of damage has occurred.  If the lawn is just slightly damaged, you can begin by following this advice to repair the grass over time:

1. If you neglect to mow your lawn for a long time, it can become over-run with weeds and moss.  This is damage; however, if it’s the only kind of damage that’s occurred, it should be relatively easy to fix.  Start by cutting only a few inches (at most) from the top of the lawn.  Let the grass start to repair itself over a few days to a week. Whilst it is, ensure that it’s properly watered.  After the few days is up, cut another few inches off. Continue doing this until the grass is at a good height.
2. Try to fertilise the grass a few times per year.  If you’ve been neglecting the grass’s health, you’ll need to intensify your fertilisation regime.  Go to any garden centre and ask for a “step system” – they’ll be able to advise you on the best kind for your soil.  These systems are useful for providing just the right nutrients at the right time to help the grass to repair itself.
3. Always kill off weeds completely (meaning to rip them up from the roots) as soon as you see them.  This helps to prevent them spreading and becoming a nuisance.
4. If any patches of grass have died and gone brown, dig up the entire area slightly (a rototiller can help with this).  After you’ve dug up the grass, spread fertiliser and seeds, cover with a thin layer of soil and water the area.  Keep the grass watered (but not drenched) every few days until the area is back to normal.
5. Of course mowing regularly, along with keeping the grass full of nutrients and well watered is the best way to keep it in its optimum condition.  When the lawn is back to a good condition, ensure you keep it that way!

This means that it’s important to keep the blade sharp to ensure the grass is cut properly. If you’re using a petrol lawnmower professionally, you may want to sharpen the blade as often as once a month. If you’re not a professional landscaper, and just use the lawnmower for home use, you can afford to sharpen the blade less often. You can check if the blade is due to be sharpened by looking at the lawn when it’s been freshly mown. Is the grass nice and evenly cut, or is it ripped and jagged? If it’s the latter, it’s time to sharpen the blade.

Warning: This is a fairly straightforward task for people who have a bit of a handy-man talent. However, if you aren’t confident in following this process, take the mower to a repair shop to have the job done. Neither PetrolLawnmowerSite.com, nor myself can take any responsibility for any injuries or other problems resulting from you following any advice on this website. The onus is on you to ensure you follow all necessary safety precautions and you don’t injure yourself or anyone else.

OK, so with that out of the way, here are some general guidelines to follow:

1. Switch off the lawnmower and take out the spark plug. Never turn over the lawnmower when it’s switched on!
2. Using a wrench, twist the nut that holds the blade in place. When this has been removed, you should be able to pull off the blade.
3. Clean the blade by using iron wool to remove dirt and rust.
4. To actually sharpen the blade, it’s often best to use a grinding wheel if you have access to one. Again, if you’re using this, follow all necessary safety precautions. If you don’t have access to a grinding wheel, using a file should do the job nicely. (Your lawnmower may have come with an included kit for sharpening the blade; if so, just use the kit.)
5. For the lawnmower to cut the lawn as evenly and well as it can, the blade needs to be balanced. If you’ve sharpened more on one side than the other, it will lose its balance. To check for this, hold the blade at its centre and see if it leans more to one side than the other. If so, sharpen the heavier side a small amount more until the blade is properly balanced.

That’s the general process and should work with most petrol lawnmowers. However, you should also read the lawnmower’s manual and check for any advice specific to your model of lawnmower.

• Firstly, don’t forget to follow safety precautions when mowing.  If you’ve opted for a petrol lawnmower instead of an electric, you won’t have the worry of running over and breaking the power cord.  However, there are a few addition precautions you should use. Check out our article on safety when using a petrol lawnmower.
• If you follow basic lawn care guidelines, you should be mowing the lawn regularly.  If you’ve left the lawn to grow for too long, mowing it all to its normal hight in one go can actually damage the turf.  Instead you should cut just a couple of inches from the top of the grass.  Leave it to repair itself slightly (for a few day to a week) and then mow a couple more inches.  Clearly this means that it won’t be at its optimum height for a few weeks, but it also means that by the time it is, it’ll be in a better condition.
• Only mow the lawn when it’s dry.  Mowing when wet causes a few problems: (1) It’s a harder job for you to push the lawnmower through the wet grass; (2) If it’s very wet, parts of the grass will be flatter than others under the weight of the moisture. Mowing it in this condition can cause it to look uneven when it’s finished; and (3) mowing when wet can actually spread fungus and moss around the lawn, causing problems to the health of the grass.
• Speaking of fungus and moss – a lot of it will grow in just one direction.  This means that if you always cut the grass in just one direction you may miss some of the weeds when mowing.  So it’s always good practise to mow in different directions to ensure you hit as many weeds as possible.
• Grass clippings are full of nutrients (see our article on lawn health).  When you’re investing in a mower (petrol lawnmower or electric), consider choosing a model that leaves the clippings on the lawn.  This lets the nutrients get reabsorbed, and means that the grass won’t need to be fertilised as often, which can help to to keep it a great shade of green.  If you’d prefer a nice tidy lawn, however, lawn sweepers are always an option (they can also really help in the Autumn for clearing dead leaves).  If you do decide to use one, make sure you have a thorough fertilisation programme for the grass.