Are Mulching Blades Supposed to Be Sharp or Dull?

Whether you have a mulching machine or mulching blades installed on your lawnmower, it’s a good idea to know how sharp they need to be. After all, if the blades are too sharp, they could slice too much debris; If they’re too dull, they won’t cut the grass evenly.

Mulching blades are supposed to be sharp so they can cut through grass, leaves, and other debris. Sharpen the mulching blades with a file until they easily cut through the grass, then tighten the blades onto the lawnmower’s deck. The blades should be sharpened twice per season.

In this article, we’ll show you how sharp your mulching blades should be and how often they should be sharpened. We’ll also provide a handful of tips to help you sharpen the blades with various tools and answer a few common questions.

Note: If you want to sharpen your mulching blades with a file, try the SHARPAL Dual-Grit Sharpening Blade. It comes with two sides to smooth out the chips and sharpen the blade quickly. The handheld tool is one of the most efficient ways to keep your mulching blades in good shape.

Do Mulching Blades Need to Be Sharp?

Mulching blades need to be sharp because a dull blade will rip the grass from the soil, ruining the lawn. Furthermore, unsharpened mulching blades can invite rust and corrosion, dulling them more and making them ineffective when it’s time to cut and use the mulch.

Here’s a list of detailed reasons you should sharpen your mulching blades:

• Your mower’s deck can get clogged if you don’t sharpen the blades. A clogged deck is one of the reasons it’s so hard to pull a mower cord. All of the mulch and grass gets caught under the deck, jamming the blades since they can’t slice through the debris.
• Dull blades won’t cut grass, leaves, and other debris. Your mulching blades need to be sharpened regularly if you don’t want your lawn to look like someone went through it with a pair of jagged scissors. It’ll also make it much easier for you to push or drive the mower.
• You should sharpen the mulching blades to prevent them from getting covered in rust. Once rust sets in from excess moisture, the blades will deteriorate and won’t work anymore. Mulching blades can develop rust from leaving the mower in the rain, cutting the grass when there’s dew on it, or storing it in a humid environment.

There are many other reasons you should sharpen your mulching blades, most of which relate to how easy and smooth you can cut through grass, weeds, and so on. Sharpened blades make a massive difference, but how often are you supposed to file them down? Read on to find out below.

How Often Should Mulching Blades Be Sharpened?

Mulching blades should be sharpened once to twice per season, depending on how often you use them. If you mulch the grass weekly or bi-weekly, it’s best to sharpen them twice. The constant cutting will take its toll on the mulching blades, dulling them quickly.

According to Home Depot, you can sharpen your mulching blades after every 25 hours of usage. The twice-per-season rule is another method, but you could follow whichever measurement comes first. If you use your mulching blades several times per week, it might be better to sharpen them every 25 hours.

Keep in mind that some mulching blades are much better than others. You’ll come across low-end blades on equally disappointing lawnmowers or mulching machines that won’t come close to the quality of a high-end mulching blade. Even if they’re sharpened, they won’t cut as well.

Failure to sharpen mulching blades is terrible for the lawn and surrounding garden, but it’s always better to start with the best blades you can get. Good mulching blades will let you grow all sorts of plants.

If you’ve never used mulch to garden, follow our guide about growing plants through the mulch. The key is to introduce enough oxygen, sunlight, nutrients, and water, so the plants can thrive.

Mulch and fertilizer can help many plants be well-drained through water retention. It’s important to sharpen your mulching blades to optimize the drainage of the mulch as much as possible.

How to Sharpen Mulching Blades

To sharpen mulching blades, follow this easy method:

1. Turn off the ignition, remove the spark plugs, and tip the mower to expose the blade’s screw. If you have a standing mulching machine, simply unplug it and loosen the blade. These machines are incredibly effective, but they take a lot more effort since you have to keep dumping the debris into them.
2. Sharpen the mulching blade with one side of a blade file. SFGate recommends sharpening it until it’s as sharp as a butter knife. The lower grit side will remove chips and rusty spots before it’s time to sharpen the mulching blades with the other side.
3. Flip the file over and sharpen the mulching blade until it’s very sharp. The higher grit sharpens it enough to finish it off, but it’s crucial to use both sides to finish the process. Using a high-grit file on an extremely dull mulching blade will remove too much metal.
4. Attach the mulching blade to the lawnmower’s deck with the screw, insert the spark plug, and start the mower. Make sure you check the spark plug to see if it’s still in working condition. Spark plugs should be replaced once per year, so it’s not a bad idea to take the time to switch them out.

The Sharpal All-in-1 Garden Tool Sharpener lets you slide the mulching blade through a file without any of the manual filing mentioned above. The ergonomic handle makes it simple and straightforward. The best part is that you can use it on knives, mower and mulching blades, garden clippers, and more.

Do Mulching Blades Come Sharpened?

Mulching blades come sharpened by the manufacturer, so they’re ready to go right when you install them. If you get a lawnmower with 3-in-1 mulching blades, they can mulch, cut grass into a bag, or discharge the grass onto the lawn or garden. These blades typically have sharper tips.

If you get a set of mulching blades that aren’t sharpened, you should send them back and ask for a new set. Mulching blades have to be sharpened, or they won’t cut anything smoothly enough. You’ll be left with shredded grass that’s uneven and broken apart.

However, some blades stay sharp longer than others. Check the metal to know if it’s aluminum or steel. Steel mulching blades are heavier, but they’re much more reliable, durable, and long-lasting than aluminum. The only time you should use aluminum mulching blades is if you want a lightweight setup for a low-maintenance lawn.

A top-shelf set of steel mulching blades will stay sharp for several months before they have to be filed. If you don’t stay on the previously mentioned sharpening schedule, keep an eye on the grass. Once it starts to look chunked or uneven, it’s time to sharpen the blades. Rust is another indicator that it’s time to sharpen them.

Whether you have a standalone mulching machine or a lawnmower with mulching blades, they have to be sharpened to do their job. A little bit of maintenance goes a long way!

Final Thoughts

Now that you know how to sharpen your mulching blades and how often they should be treated, you can ensure you’re always cutting the grass smoothly and evenly. Dull blades can cause all sorts of issues, and it only takes a few minutes to bring them back to top-notch condition.