Mower Leaving Strips of Grass (Here’s Why)

There’s nothing nicer than looking back at your lawn when you’re finished mowing and thinking, it’s perfect. All your time and effort has been well spent. But sometimes you look at your freshly mowed lawn and think, what is going on?

Being unhappy with your mowed lawn can happen for several reasons, like when your lawn mower leaves strips of grass. So, what’s going on? Why doesn’t the yard look as good as it normally does? Well, let’s take a look.

Why Does My Mower Leave a Strip of Grass? (The Short Answer)

Having a strip of uncut lawn in your path is usually down to something getting in the way of the blade in the deck, dull or damaged cutting blades, the height of the wheels being unevenly set, not overlapping your passes, or cutting the lawn when it is wet.

A Closer Look at Reasons for a Lawn Mower Leaving Streaks

If your lawn mower is leaving a line of uncut grass, then you might need to make an adjustment. This could be something to do with your cutting method or something wrong with the lawn mower. Let’s take a closer look.

Not Overlapping the Cut

The first thing to check is whether you overlap between strips as you mow. If you are cutting a bit wide and not overlapping where you’ve passed, then you’ll end up missing sections of the lawn. So, if you notice an uncut strip being left behind you, then stop mowing and check the position of your lawn mower. If you see that there is a gap between passes, then you’ll need to adjust your spacing.

Cutting the Lawn When it is Wet

Trying to mow a lawn when it is wet can be a real problem for your lawn mower. The blades really struggle to cut wet grass as the blades just slip off the cutting edge and end up not cutting correctly. Also, wet grass can be too heavy for the blades to lift, so the lawn mower ends up leaving a trail of clumped clippings instead of evenly spreading them over the lawn. So, take a look at the lawn and clippings and see if they are wet.

Blocked Cutting Deck

Cutting decks can get overloaded with clippings if the grass is long or even if the grass is wet. This means the grass isn’t thrown out of the chute correctly and ends up falling back on the lawn within the deck.

Now, if there are enough clippings unable to escape, they can get in the way of the blades as they try to cut the lawn. Also, you’ll find that your lawn mower starts to build up clippings on the inside of the deck as you cut. This is because the moisture within the grass blades acts like glue to stick the clipping to the deck’s surfaces.

Over time there can be a big enough build-up that an obstruction is caused, and the clipping can’t be discharged correctly. So, tilt over your lawn mower and take a look at what is going on underneath.

Dull or Damaged Blades

Another common reason for a lawn mower leaving a line of uncut grass is because of dull or damaged cutting blades. It’s normal to notice your blades start to cut less effectively over time as they lose their cutting edge.

This can be accelerated if you hit the odd rock or stump, as this will cause chips and dings in the blade’s cutting edge and reduce the blade’s cutting ability. So, tilt over the lawn mower and take a look at the blade’s cutting edge.

Wheels Not Set Correctly

Lawn mowers use different methods to adjust the cutting height of the blades. For lawn mowers that require each wheel or pair of wheels to be set independently, it’s common for them to be set incorrectly.

If you have ever sat on a chair on uneven ground, then you know how wobbly it can be. This is the same for a lawn mower. If all four wheels are not set correctly, then the lawn mower will be unstable and easily leave a strip of grass as you mow. So, check the height settings of each wheel and see what they are set to.

Fixing a Mower That Leaves Strips of Grass Uncut (5 Things to Try)

After asking myself over and over, why does my mower leave a strip of grass? I decided to make some changes. Here’s what I did to my lawn mower to stop it from leaving a line of uncut grass.

Perfecting Your Overlap

Usually, you’ll find that the front wheels on your push lawn mower are the same width as the cutting blade and the over-cutting width. So, as you turn your lawn mower to cut the next strip, place your wheel onto the wheel mark from the previous strip. This will help you avoid missing any grass by cutting it too wide.

Now, if you have a reel lawn mower, you might need to cut even narrower passes as the wheels sit on the outside of the mower.

Picking the Right Time to Mow

An easy way to avoid the problem associated with mowing a wet lawn is to simply cut when the lawn is dry. I know this is easier said than done sometimes, as it can be rainy for several weeks, leaving you with constant wet grass. So, it is one of those situations where you have to make the best of a bad situation.

Now, you could just accept the strip and the clumping grass, or you could double-cut the lawn. By this, I mean cutting the lawn twice. Another option is to mow the lawn on a higher height setting, so the lawn mower has an easier job.

Cleaning the Cutting Deck

Cleaning out the deck is a task I make sure to do after every cut. Well, nearly every cut. I tend to skip a few cleanings if the lawn is nice and dry. But if you find the deck is starting to build up with clippings, you’ll want to tilt over the lawn mower and remove any clippings.

I find the best tool for the job is an old 2-inch paint scraper I have in my garage. It’s just the right size to navigate around the inside of the deck and scrape off the clipping and dirt.

Sharpening the Blades

Sharpening your blades is something you should be doing at least once per season or any time that they become dull. How often you sharpen your blades can have a really big impact on how your lawn mower cuts and is a potential reason your lawn mower is leaving streaks.

To do this, you’ll need to tilt over your lawn mower and remove the blade. Then you’re going to pick your blade sharpening method and grab either a metal file, angle grinder, or bench grinder and sharpen the mower blade. Just remember to sharpen your lawn mower blade to the proper angle.

Finally, reinstall your blade, and you’re ready to go. Now, if you have trouble getting your lawn mower blade off the mower, then there are certain methods you can use to sharpen your blade without removing it, so there are no excuses for a dull blade.

Adjusting the Height Settings

There are several different methods to adjust the cutting height of your lawn mower, depending on your mower. Unfortunately, there isn’t one universal method. So, you’ll need to do a little research if you’re unsure.

The key to the process is to set the height evenly on all of the lawn mower’s wheels. This will stop the wobbling and hopefully prevent your mower from leaving strips of grass.

Riding Mower Leaves Strips of Grass – Anything Else I Need to Know?

Now that I have covered the common reasons a push lawn mower is leaving streaks, it’s time to take a look at some bigger mowers. So, if you’re wondering why does my riding mower leave a strip? Then, here are a couple of potential reasons.

Correct Tire Pressure

If you have incorrect tire pressure, then you could be back in the wobbly chair situation, like setting the height incorrectly on a push lawn mower. So, grab yourself a tire pressure gauge and test each tire.

If you’re checking the tire pressure on a zero-turn or a tractor lawn mower, you’ll need to check the max psi number stated on the wall of the tire. Then use this number to inflate the tire to the correct pressure.

I always like to inflate my tires just below the max rating so that I don’t end up over-inflating and causing a problem.

Leveling Deck

If you still have problems with your riding mower leaving cut grass and you have tried my other points, then you might need to check if the cutting deck is level. Having an unlevel deck is just like having a flat tire or an incorrectly set height.

You’ll need to grab a few tools and measure the deck, then potentially level the cutting deck if it’s not right. The basic principle is that the blade must be at an even height from side to side and back to front. So, make sure your lawn mower is on level ground, and the tires are inflated to the correct pressure, then measure the blade tips.

If you find that your measurements are not the same, you’ll need to make a couple of adjustments. This can be done using the adjustment feature on your riding lawn mower.

Slowing Down the Lawn Mower

I know that sometimes we are in a bit of a hurry to cut our lawns and end up riding our lawn mowers at their top speed. Unfortunately, this can cause uncut grass to be left behind you.

This is because the cutting blades require a certain amount of time to be in contact with the grass to make a nice clean cut.

So, if you are thundering across your lawn, then speed might be a problem. Also, slowing down will help you get straight lines and maintain the overlay you need.