The last thing you want when trying to have the best lawn on the block is a scalped lawn. Short yellow grass isn’t a great look and definitely isn’t going to win any prizes. So what is going on, and why is your riding mower scalping your lawn? Well, there are lots of reasons why your mower could be scalping your yard. Let’s take a look.
Riding Mower Scalping Your Lawn? (The Short Explanation)
A riding mower scalping a lawn can happen for a number of reasons ranging from how the mower is set up, the mower needing maintenance, and how the lawn mower is used. Here are several common issues that cause a mower to scalp a lawn.
- Incorrect Mowing Height
- Cutting Blades Not Installed Correctly
- Scalping Wheel Not Set to the Correct Height
- Bumpy Lawn
- Mowing Too Fast
- Repetitive Mowing Pattern
- Low Tire Pressure
- Cutting Deck is Not Level
Why is My Riding Mower Scalping (Closer Look At Possible Causes)
As you can see, there is a long list of reasons why a riding mower can scalp a lawn. Let’s take a closer look at the possible causes and see why your mower is scalping the grass. I’m pretty sure one of these causes will be the reason you’re having an issue.
Incorrect Mowing Height
Scalping happens when your lawn mower blades are cutting too low, and you end up cutting your lawn much lower than you planned. So the first place I recommend you check is the height adjustment lever on your lawn mower. The adjustment lever on your riding mower should be a handle positioned on the top/side of the mower within easy reach when you are in the seat.
Cutting Blades Not Installed Correctly
As strange as it might seem, installing a lawn mower blade upside down is pretty common. I’ll admit I’ve done it a few times myself when I wasn’t paying attention, only to realize my mistake when my lawn mower started scalping really badly.
So, look at the cutting blades under the deck and check which way you have them installed. If the flat side of the blade is facing up, or the teeth of a mulching blade are facing downwards, then you have installed the blades upside down.
Scalping Wheel Not Set to the Correct Height
If you look at your riding mower cutting deck, you may find that you have a few extra wheels. These are the anti-scalping wheels. When you set up your lawn mower for the first time, you’ll want to set up the anti-scalping wheels to ensure that your cutting deck can’t get too close to the ground. If you didn’t know that this was something you should do, then the wheels probably aren’t doing their job properly.
One way to check is to take your lawn mower to the area of your lawn that is being scalped, lower the deck to the required cutting height, then check if the anti-scalping wheels are touching the floor or not. If the wheels are off of the ground, then you’ll need to adjust them so that they work. This should stop your lawn mower from scalping in the future.
One factor about riding mowers is that their cutting decks are typically much larger than a smaller push mower. Therefore, a riding mower is much more likely to scalp your lawn if you have a few bumps in the yard. So, take your lawn mower to the area of your lawn that is being scalped and check the deck to see if it is getting closer to the ground as your mower passes over the bumps.
Typically, you will find that a bump smaller than the width/length of the cutting deck will be scalped as the mower passes over it. So with the combination of a bumpy lawn, the sheer weight of the mower, and the anti-scalping wheels not adjusted correctly, you could run into quite a bit of scalping.
Mowing Too Fast
If you drive your lawn mower too fast while mowing, this could be another reason your mower scalps the lawn. Even if your lawn is nice and flat, you’ll still find that your mower will bounce a little and begin scalping. This is especially true when it comes to fast-riding lawn mowers such as zero-turn mowers.
So, when you are mowing, check to see if your mower is bouncing and scalping at the same time. You’ll probably find that as your mower comes down from a bounce, the tires compress, and the cutting blades scalp the grass.
Repetitive Mowing Pattern
If you have a push mower, then changing up your mowing pattern isn’t really a top concern. However, when it comes to riding lawn mowers, you’ll definitely want to consider alternating the mowing direction. This is because a riding lawn mower is significantly heavier than a push mower, and over time, your riding mower will begin to leave tracks in your lawn.
These tracks compress the soil and cause your lawn mower to sink lower into the ground. As a result, the lower your mower sinks, the lower your lawn will be mowed.
Low Tire Pressure
Now if your riding mower scalping your lawn is an issue that has just started, then it could be down to low tire pressure. For example, the lower the tire pressure, the lower your lawn mower will sit on the ground, and the lower your lawn will be cut. So, grab yourself a tire pressure gauge and check all of the tires. If the tires are not inflated to the recommended pressure, then it’s highly likely that this is why your mower is scalping.
Cutting Deck Not Level
Part of regular mower maintenance is to check and adjust your cutting deck to ensure that it is level. Now if your mower’s cutting deck has been bounced about a lot, then it’s common for the deck to drop on its mounts and hang to one side. In really bad cases, both sides can drop. So, when setting your lawn mower to your preferred cutting height, you may actually be setting it too low without realizing it.
An easy way to check if your lawn mower cutting deck is level is to place your lawn mower on a flat surface, then measure the distance from each blade to the ground. The left blade and right blade should be at an equal distance from the ground. If the measurements are different, then you’ll have diagnosed that your deck isn’t level.
How to Fix a Riding Mower That Scalps the Lawn (X Things to Try)
Hopefully, one of the above possible causes has helped you answer the question, why is my mower scalping? Now, let’s go over all the different solutions you can try. Let’s take a look at how to stop your riding mower from scalping your lawn.
Set the Cut Height to the Correct Setting
The steps for adjusting the cutting height on a riding mower are just a case of adjusting the lever to the right number. So if you are scalping your lawn, you’ll want to raise the lever to a higher number. Now it’s also worth noting that the numbers on the cutting height adjustment lever don’t always refer to the actual height measurement the blades cut at. They are typically just there for reference. If you want to be super accurate, then you can measure the distance the blade is from the ground at each height setting. This will give you a clear understanding of what the numbers mean so that you can get an accurate cut height.
Install the Cutting Blades the Right Way Up
So if you have installed the cutting blade the wrong way up, you’ll likely know how to sharpen a lawn mower blade, and you probably already know the correct angle to sharpen a mower blade. Now, it’s just a case of getting the blade installed the right way up. I find the easiest way to ensure you don’t make this mistake again is to label the blade.
So, before installing the mower blade, use a permanent marker to label the bottom of each blade. Then, if you get under your lawn mower, you’ll know that the side of the blade you have labeled is the bottom, which is the side that you should still be able to see once the blades are installed.
Adjust the Anti-Scalping Wheels
When it comes to adjusting a mower’s anti-scalping wheels, there is no real difference between adjusting 2 Vs. 4 anti-scalping wheels. It’s just a case of setting them all to the same height. So, most riding lawn mowers, including tractors and zero-turns, have a few different height options to which you can set the wheels. All you really have to do is pick the right option that suits your lawn the best.
For example, when I set my wheels, I start at the lowest setting and then give my mower a try. Now for me, this setting works fine, but for you, it may not. So you’ll want to try the different height settings and figure out which position stops the scalping but still gives you a low enough cut.
Typically, scalping wheels are attached to the lawn mower with a bolt that passes through the scalping wheel, or the wheel is attached to a yoke. In either case, to adjust the wheels, you just have to remove the bolts, reposition the wheels, and reinstall the bolts.
Tools to Adjust Anti-Scalping Wheels
- Socket Wrench Set
- Wrench Set
Leveling Your Lawn
Leveling a lawn is a pretty big topic and can be tackled in a number of different ways. But simply put, you really have two choices. You either roll out the bumps or add fill material to raise the surrounding lawn. Either method will reduce the high and low spots and stop your riding mower from scalping your lawn.
Now if you choose to go this route, then you want to make sure you follow a good method, as there are a lot of lawn leveling mistakes that you will want to avoid, such as using the wrong fill material, leveling wet ground, and not using the right tools.
Adjust Your Mowing Speed
If your lawn mower is scalping because you are going too fast, then all you need to do is slow down and take it a bit slower. Riding mowers have extra speeds, which makes some guys like to mow as fast as possible. While it means you can mow the yard faster, it can easily cause scalping.
So, try lowering your speed and see if this makes a difference. Also, improving your driving ability and skill will have a big effect when it comes to scalping. So, if your zero-turn is a bit jerky, try slowing down.
Cross-Cutting With a Riding Mower
Cross-cutting with a riding mower is a case of cutting in one direction for one week and then changing it up the following week. For example, one week, you mow side to side, then the following week, you mow up and down your lawn. Alternating mowing patterns basically give the tracks created by the lawn mower wheels more time to recover.
Using just two lawn mower patterns and techniques will extend the recovery time from one week to two, prevent the soil from sinking, and reduce scalping. Also, the tracks will become less visible as the lawn recovers from excessive compaction.
Inflate Riding Mower Wheels
When figuring out the best tire pressure for a zero-turn mower or a tractor mower, you’ll want to either check the rating on the side of the tire wall or take a look in the manual that came with your lawn mower. Once you have the correct PSI rating, you can use a tire inflator to inflate your tires to the correct level. Then, hopefully, the lawn scalping will either reduce or disappear altogether.
Tools to Inflate Riding Lawn Mower Tires Correctly
- Tire Inflator or Pump
- Tire Pressure Guage
Riding Mower Deck Leveling
Deck leveling can vary from one riding mower to another, but the method tends to be the same. So what you need to achieve is leveling the deck from side to side and then from back to front. Here is an overview of how to level a mower deck that should have you covered.
Mower Deck Leveling Preparation
- Place the lawn mower on level, flat ground.
- Ensure that the tires are correctly inflated
- Ensure that all the cutting blades are in good condition and that they’re not bent.
Side to Side Mower Deck Leveling
- Position the left blade so the blade tip points out to the side.
- Measure the distance from the blade tip to the ground.
- Repeat steps 2-3 for the right blade.
- Compare the results of the left and right sides.
- Adjust the left side of the deck or the right side of the deck so that both measurements are equal.
Front to Back Mower Deck Leveling
- Position the center blade so the blade tips point front to back.
- Measure the distance from the blade tip to the ground of the blade tip pointing forward.
- Measure the distance from the blade tip to the ground of the blade tip pointing backward.
- Adjust the cutting deck so that the rear blade tip is ½ inch higher than the front blade tip.
Tools to Level a Lawn Mower Cutting Deck
- Measuring Tape or Ruler
- Wrench Set