How to Keep Grass from Sticking Under the Mower Deck?

This is such a common problem. Everyone who has ever mowed their lawn more than a few times has experienced grass sticking under the mower deck. It’s a pain in the butt, not just because it takes time to clean it off (especially if you let it dry on – boy that can be a nightmare), but also because if you don’t remove this build-up of clippings, it can have some pretty serious consequences for your mower and worsen its performance significantly.

But how do you keep grass from sticking under the mower deck? That’s the million-dollar question. There are a few different things you can try including adjusting your mowing habits, and coating the underside of the deck with a few different substances such as cooking spray or a product like Fluid Film.

Which one works best? – I’ll discuss my favorite method in this post. But first things first – why is the grass that sticks to your mower’s undercarriage so bad?!

Why You Need to Prevent Grass Build-Up on the Underside of the Mower Deck

Keeping the mower deck clean and free of clippings is not something you just do for show. It’s not because you want your mower to “look its best” (you don’t actually ever see under the deck anyway unless you lift it up…). It’s important as the consequences of not doing so can be pretty serious. These include:

Chutes Becoming Blocked

The build-up of clippings will eventually start to narrow the openings to the grass catcher and the discharge chute, which in turn will cause more clumping and more build-up on the undercarriage. It’s the definition of a vicious circle. Bad for your mower and bad for your lawn, as clumps that are left behind can promote the growth of things like lawn fungus.

Related Article: How to Keep Grass From Clumping When Mowing

Deck Becoming Corroded

Wet grass stuck to a metal deck for long periods of time is a recipe for disaster, and can result in the deck corroding. If that happens, you’re in a tricky situation. You may well have to get a new mower. Another rather unpleasant side-effect of a mower deck coated in wet clippings is mold and mildew. And that stinks when it’s left to fester in a garage or shed. Trust me!

More Strain on Your Mower

Your mower won’t be anywhere near as efficient if airflow is reduced and the exit chutes are blocked, which forces it to work harder and harder to try and deliver the cut. This is not good for your mower, especially the motor, and can reduce its lifespan significantly.

Increased Fuel Consumption

The added strain placed on the mower will usually also result in it using more fuel to mow the same amount of lawn. So not only are these clippings shortening your mower’s lifespan, they’re costing you more in fuel too!

Poor Performance

Last but not least, the mower that you once respected so greatly for the job that it did is now barely scraping a C-.  What is happening???

We know the problem, so let’s now focus on how to prevent grass from sticking under the mower deck.

A Few Adjustments that Can Reduce Grass Sticking Under the Mower Deck

The first thing that I’d recommend you do is make the following adjustments. Now, these aren’t going to eliminate the grass build-up altogether, but they can definitely help to reduce it. And they’re easy to implement. So why not do it?!

Mow When It’s Dry

Now, this might sound pretty darn obvious, but you’d be surprised at just how many people don’t connect the dots. Mowing wet grass always leads to more clippings sticking to the mower deck. Wet grass = sticky grass. Just by only mowing when it’s dry, you can reduce the amount of build-up you see under the deck by quite a bit.

Cut More Often

Little and often is the absolute key when it comes to mowing. If you let your grass grow too much, the clippings are much longer and there’s more chance of clumping and build-up under the deck. There are soooo many benefits to keeping on top of your mowing, and this is another one.

Related Article: How Often Should I Cut My Grass?

Keep Your Mower in Good Condition

Another kind of obvious point. None of this is rocket science. If your mower is only working at 50% of its capacity, and is struggling to eject the clippings out from the deck once they’ve been cut, they’re more likely to stick to it. So by keeping your mower in tip-top condition you can lessen the chances of this. Regularly check that the air filter is clean and not clogged, and check oil and gas levels.

Now that we’ve covered a few basic adjustments, it’s time to talk about products you can use to help stop grass from sticking under the mower deck.

How to Stop Grass from Sticking Under the Mower Deck: Some Coatings You Can Apply

One thing that needs mentioning before we get to discussing the potential solutions that I’m going to share is that the deck must be clean before attempting to coat it in any of these substances. Applying them to a deck that is already coated in clippings will have no impact at all. So don’t waste your time and money by doing that. Fully clean the underside of your deck first so that there are no clippings whatsoever. Obviously, if your mower is new you can ignore this.

Just to be clear, I’m yet to find a product that will 100% prevent grass from sticking to the underside of a deck. Some grass varieties are also worse than others for this problem. But here’s a few things that I have personally found to be worth trying:

Non-Stick Cooking Spray/Vegetable Oil

This is a very cheap and easy solution to try, since you probably already have some at home. I’ve found that it helps to reduce the amount of clippings that stick quite significantly, although it’s a short-term solution. You’ll need to apply it regularly to see these benefits. Some people will probably tell you to use WD40 or used engine oil, which both have a similar effect, but if they get on the lawn they can be very harmful to it, which is why I prefer cooking spray/oil (I like Pam oil).

Fluid Film

I use Fluid Film now and it does a pretty good job. Again, it doesn’t eliminate build-up completely, but it definitely helps to reduce it, so you don’t need to do a full clean quite so often (although I have to say, I’m a big fan of giving the deck a quick wash after every mow – don’t give the clippings a chance to dry out).

It also protects your deck from rusting, so you get two benefits for the price of one. It’s not the cheapest solution to this problem, but the best option is not always the cheapest…

DuPont Non-Stick Spray

This is not a product that I’ve personally used but it’s something that I’ve heard good things about and it has good ratings. It applies a non-stick dry-film Teflon coating to the surface underneath your mower deck to prevent clippings from accumulating. It’s been on my list of “need to try” items for a while. If you get around to using it before me, let me know!

Final Thoughts: There’s No Solution that’s 100% Effective

The build-up of grass clippings on the underside of a mower deck is a necessary evil. Whatever you do, you’re going to get some sort of build-up on the deck (I hope I’m not bursting anyone’s bubble…). BUT…you can reduce that build-up significantly by following the tips we’ve discussed above (I’d go for Fluid Film + the mowing adjustments mentioned). And that makes it much easier when you clean the deck – there won’t be anywhere near as much caked on, and it’s going to help keep your deck in much better condition for longer.