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Why Is My Lawn Mower Leaving a Strip of Grass? Solved!

The invention of lawnmowers made things a lot easier on homeowners who prefer having a manicured lawn, but even the best mowers have trouble from time to time. Luckily, many of these problems have simple solutions, and you can find the answers to some of the most prevalent issues below.

Although there are several reasons why a mower might cut grass unevenly, strips of grass are frequently the result of user errors or problems with the blades and or mowing deck.

Continue reading to learn more about the most common mowing problems and how you can avoid them this mowing season.

Strip of uncut grass

Staying Safe While Troubleshooting Your Mower

Each year, the United States sees an average of 6,390 lawnmower-related injuries, and not one of them is planned. Although these accidents range in severity, the one commonality between all of them is that the users thought they would be fine. If you find yourself having to fix your lawnmower this season, please make sure to follow the safety tips listed below.

  • Familiarize yourself with the owner’s manual and how the machine works.
  • Check to ensure that all safety features are engaged.
  • Turn the machine off and remove any keys.
  • Disconnect the spark plug wire to ensure the engine cannot run.
  • Do not override any safety features—even if they are annoying.
  • Keep guards installed whenever you are not working on the machine.
  • Wear gloves and long sleeves when working or cleaning around sharp blades.
  • Wear sneakers or boots and avoid wearing open-toed shoes when mowing.
  • Never operate or work on a lawnmower when under the influence of any substances.
  • Work on the machine during the day or in a well-lit area.

Now that you know how to keep yourself safe, let’s look at some of the most common law mower problems.

Why Is My Mower Leaving Strips of Grass?

Also known as streaking, this problem occurs when strips of grass are left uncut by your lawnmower. Although there are several reasons this might be happening, it is typically caused by blade problems or user error.

Potential CausesPotential Solutions
Dull BladesHave blades sharpened
Warped BladesReplace warped or damaged blades.
Improperly Installed BladesMake sure blades are the correct size and are installed correctly.
OverlappingOverlap cutting rows by 1 to 2 inches.
Clogged DeckClean dirt and debris out from under the deck.
Incorrect SpeedRefer to the manual for the optimal speed.

Blade Problems

Lawnmower blades become dull and damaged over time, which is why owners should inspect their blades at the beginning of the mowing season. Dull blades can be sharpened, but if the blade is bent or warped, they will need to be replaced. Improper installation is another frequent problem, with many people finding that they accidentally installed the blades upside down.

User Error

Because the blades do not go all the way to the edge of the deck, and the grass under the tires does not get cut, you will need to overlap your last pass by one to two inches. Additionally, make sure that you have the correct size blade installed.

Deck Issues

If you know the blades are fine, and you are mowing as you should, the issue may lie under the deck. Mud, grass, and other debris can get caught up under the deck, causing clogs that can affect how the mower operates.

Why Does My Lawn Look Uneven After Mowing?

Also known as stepped cutting, this occurs when the grass is cut at an uneven angle. While there are several reasons this might happen, it is most commonly the result of an uneven deck or misaligned blades.

Potential CausesPotential Solutions
Incorrectly Installed BladesMake sure the blades are facing the correct direction and are not warped.
Loose or Damaged SpindleCheck the mower spindle and repair it if necessary.
Damaged DeckCheck if the deck is level and if not repair or replace it.
Flat TiresUnderinflated tires will cause one side to sit lower and cause uneven cutting. Check tire pressure.

Blade Problems

Stepped cutting is often the result of misaligned blades. The blades are either not installed correctly or have become warped somehow (usually from hitting something), resulting in an angled cut. Repairs will depend on the condition of the blades and could be as simple as readjusting them or as difficult as replacing them entirely.

User Error

Although less common, stepped cutting can sometimes be the result of user error. However, this has more to do with the user not properly maintaining the machine. For example, if the tires are low or flat on one side, it could result in an uneven cut.

Deck Issues

Damaged or unleveled decks will not hold the blades straight, causing them to instead cut at an angle. Use a bubble level to check if the deck is sitting straight. If not, you can try adjusting the level, checking that the tires are all properly inflated, or looking for any damage to the deck itself.

Why Does My Lawn Look Choppy After Mowing?

Commonly referred to as patchy, this occurs when a mower leaves behind patches of uncut grass in no particular order. Although this can occur for several reasons, it is most commonly due to problems with the blades or user error.

Potential CausePotential Solution
Dull or Damaged BladesSharpen or replace the blades.
Low Throttle SpeedsMost mowers should be run at full throttle but refer to your user manual.
Fast SpeedsTry reducing your speed if you notice patches.
Clogged DeckClean under the deck and around blades.
Loss of PowerDo not use multiple extension cords with an electric mower.
Wrong MachineDo your research and make sure you purchase the right machine for your lawn needs.
Constant PatternsSwitch up your mowing direction and pattern occasionally to ensure grass grows straight up.
Poor MaintenanceMaintain your lawn and machine regularly.

Blade Problems

Dull blades are not able to cut the grass as effectively and instead will rip and tear the grass. Additionally, if the blades are uneven, they can rut up the ground, causing it to become uneven. If the blades are just dull, you may be able to sharpen them. However, damaged blades will need to be replaced.

User Error

A patchy or choppy lawn might also be the result of the wrong lawnmower. Make sure that you are using the right machine for the job. Additionally, speed and power play a significant role in the quality of your cut. For example, if you go too fast, the blades might miss some areas of grass, and multiple extension cords could reduce the power of an electric mower.

Another lesser-known complication happens when users mow in the same direction every time. Eventually, the grass becomes used to this and will start to grow in the direction that you mow.

Finally, maintenance is important—both to your machine and lawn. If you do not maintain your machine, it will not work properly. Be sure to keep up with its recommended service and store it properly during the winter. Maintaining your lawn is also important.

Be sure to rake up large clumps of clipping to avoid dead spots and fungus. You should also avoid mowing while your lawn is wet because you can damage the grass and create ruts in the soft soil.

Deck Issues

Checking for deck issues is always a good idea when you notice your lawn looks choppy. Tall or wet grass will often cause clogs that can hinder the vacuum operation and inhibit the blades. Additionally, if the machine is not used at the correct throttle position, it can cause the mower to leave patches of grass behind.

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