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How Often Should Lawn Mower Blades Be Replaced?

Are your mower’s blades up to the task? Knowing when to replace them can make all the difference in your lawn’s appearance. With our guidance, you’ll be able to make an informed decision.

Lawn mower blades should be inspected before each mowing season. Sharpen blades if they are nicked or bent. Replace very thin blades. Sharpening good blades once per year is usually sufficient. Follow directions to remove, replace, and adjust the blades properly before mowing again.

Want to ensure your lawn always looks its best? The condition of your mower’s blades plays a crucial role. Read on to learn how to identify worn-out blades and the steps to take for maintenance or replacement.

When you Need to Replace Your Mower Blades

Once your lawn mower blades get damaged or probably when the blades have been sharpened too many times, it is recommended that you either replace them with a set of used blades (in good condition), or an entirely new set of blades.

Generally, regardless of the frequency by which they are used, lawn mower blades tend to get dented, worn and damaged easily, especially when they hit hard objects like rocks and wood chips.

Hence, if you haven’t changed your blades in a while but have sharpened them multiple times, you should consider replacing them to avoid damaging your mower. Below are a few signs to look out for to know if your blade needs to be sharpened or replaced.

● Uneven Length of Grass

One of the first things you’ll notice when mowing with a blunt blade is that your lawn won’t look as great as it usually does. You may notice uneven patches or realize you must cross your lawn several times before cutting right.

This is because using a dull blade will require much more effort to mow your grass, and you’ll even need to compensate for the missed patches to get the desired results. However, if you’re cutting with a sharp blade, you’ll realize that you easily make passes over your grass once, and each piece of grass is cut to the same height.

In my 20 years of experience, I’ve found that uneven grass cuts, excessive vibration, and visible blade damage are clear signs that a lawn mower blade needs to be replaced.

So, if you notice that mowing has become more of an effort and is more time-consuming than usual, it is likely a sign that your lawnmower blade needs replacing or sharpening. Typically, it’s a good idea to buy new lawn mower blades or sharpen old mower blades.

If your new lawn isn’t as good as it typically is, it might be time to buy new blades or sharpen your existing ones.

● Torn or Uncleanly Cut Grass

Another sign to look out for is how your grass looks after cutting. After mowing your lawn, inspect it to see whether each piece of grass is cut. If you notice that the grass blades look torn rather than cleanly cut, it may be time to sharpen or change the old blades.

If you ignore and cut your grass with a dull blade, it can affect the overall health of your grass, causing it to lose its lushness and fresh green color and even encouraging the growth of grass diseases and infections.

Before this condition occurs, you should replace your blades as soon as possible, as damaged blades can be very harmful to the health of your lawn.

● Condition of the Blades

Another way to know if your lawn mower blade needs replacement is to inspect the blade itself. Usually, you should be able to keep your old blade once it is sharpened. However, if you notice chips or large dents in the blade, you may need to replace it.

Also, it would be best if you looked out for the thickness of your blade as it can erode over time due to the compilation of debris like sand and dirt. All these can cause the metal to become thinner and weaker.

Once you notice this, then it is time to replace the blade. It is generally safer to replace the blade immediately after seeing any problem than to wait for it to break during use. If a blade breaks when you’re mowing, it can be hazardous as a piece of metal might fly off and injure you or anyone nearby.

How Often Should Lawn Mower Blades Be Replaced?

As a general rule of thumb, it is recommended for an average homeowner to sharpen their lawnmower blades at least once a year, at the start or end of the mowing season. Check if the blade is not dented, chipped, worn out, or has other damage. In that case, the blade needs to be replaced.

Of course, if you hit a hard object, the blade must be checked immediately. This guide on mowing best practices is part of the resources available on our blog and portal. We aim to provide comprehensive guides and resources for lawn care and maintenance.

If you need replacement lawnmower blades, we have various options available. Just let us know, and we’ll assist you in finding the right fit for your mower. Remember, whether you choose to sharpen old ones or get new blades, the health of your lawn depends on it. Happy mowing!

Before you start to replace the blades yourself, you must inspect them properly and consult the user’s manual that comes with it to know about the safety instructions, warranty, and the right blade to use.

I recommend wearing protective equipment and heavy-duty gloves when working on your mower’s blades. There are some common errors homeowners make when it comes to replacing the blade of their lawnmower. These include:

  • Sharpening too often: I think that sharpening mower blades regularly will prolong their lifespan.
  • Replacing instead of sharpening: Replacing the blade even though it can be sharpened
  • Emptying the fuel tank: Not emptying the fuel tank before tilting the mower to its side
  • Wrong direction: Fixing the blade in the wrong direction
  • Experience: Trying to replace the blade without prior experience.

From my two decades in the field, I can say that a typical homeowner should replace their lawn mower blades every 1-2 years, but this can vary based on usage

How to replace lawnmower blade: Tips and Tricks

You can replace the blades of your lawnmower in the few easy steps below

Step 1. Disconnect the ignition wire and drain the gas:

Disconnect the ignition wire from the spark plug. If you’re using a cordless mower, remove the battery pack. This is to prevent the risk of the engine accidentally starting up while you’re working. It would be best to drain the gas tank so it won’t spill any fuel while you’re working on the blades.

Step 2. Tilt the mower:

Tilt the mower to expose the nut or bolt that secures the blade to the mower. Wedge a short wood block between the blade’s end and the mowing deck’s inside surface to keep the blade from turning.

Then, use a wrench and socket to loosen the nut or bolt. You can slip a metal pipe over the wrench handle to increase the leverage when reducing any stubborn fastener.

Step 3. Remove the blade mounting bolt:

Use a socket wrench of the appropriate size and unbolt the mounting while using your other hand to keep the blade from turning. Be careful not to lose any washers or mounting hardware that hold the blade into place, which can be reused.

Step 4. Note the position of the blade:

Remember to note which side of the blade faces downward mentally. It’s essential to bolt back the blade in the same orientation.

Common mistakes I’ve seen when replacing lawn mower blades include over-tightening the bolt, installing the blade upside down, and not replacing a bent blade.

Step 5. Mount the new blade:

Mount the new blade in the right direction. Line up the blades as they were lined up and reinstall the washers and nuts. If you have the owner’s manual, you should find the torque specs for tightening the nut. If you don’t, ensure you don’t over-tighten it, as this can cause vibrations in the mower.

Also, be sure that the length of the blade is the same as the old one before mounting it. Tighten the new blade to the bolts carefully since it’ll likely be sharper than the old one. Make sure you’re wearing heavy-duty gloves when doing it, to prevent any injury.

Step 6. Check the blade:

Ensure the blade is mounted correctly and firmly and has no wobble when you move it up and down. Remove any props that hold the mower in place and wait 30 to 60 minutes for the oil to return to the motor to prevent motor damage.

Step 7. Reattach the spark plug wire:

Refill the gas tank and reattach the spark plug wire. Then, do a quick inspection before mowing. Check the air filter to ensure oil does not saturate the foam filter. After a quick inspection, your mower should be able to run and start cutting grass much more efficiently than before!


That being said, the best way to know if and when your lawn mower blade needs to be replaced is to pay close attention to the condition of your grass. Also, inspect the blade regularly, which will help you determine whether your lawn mower blade needs to be sharpened or replaced. Good luck!

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