Ideally, we should be regularly cutting our grass, preventing it from getting too tall.
But in reality, things are not always how they should be. We may end up being too busy, going on a vacation, having a long break, working extra time, or maybe the lawn mower is out of service for some reason.
That way, we can easily end up with a big gap between now and the next mowing session, during which the grass can grow to be super tall. So what do we do then?
Can a lawn mower cut tall grass? Lawn mowers’ top height position usually goes up to 4 inches. However, grass that is 6 to 8 inches tall can be cut with a lawn mower by setting it in the highest position possible. For grass taller than 8 inches, you will need to use a weed trimmer first.
While I was doing my research on the topic, I was able to find a lot of interesting information on cutting tall grass with a lawn mower.
Below I will share with you everything I found in order to help you maintain your lawn in the best condition possible.
What Are the Disadvantages of Mowing Tall Grass?
There are a few things that might happen if you try using your lawn mower for cutting grass that is way too high.
Potential Mower Damage
First, there is a high chance that you will be putting your lawn mower’s motor under a lot of stress – more than what it has been designed to deal with.
Of course, there are some very powerful lawn mowers that will definitely not feel the burden of cutting long grass, but it is dangerous nonetheless. Either way, keep your mower’s specs in mind before trying to cut overly long grass.
Hitting Foreign Objects
There is a risk of hitting a foreign object that may be hidden in the tall grass. This can potentially damage the lawn mower and its blade(s) and is also a potential health and fire hazard as well.
Before you start, make sure to inspect the lawn and remove any debris, sticks and branches, rocks, or any other foreign objects.
How to Cut Tall Grass?
Because there are literally hundreds of different lawn mowers out there, I will recommend double-checking with your owner’s manual before starting out.
From experience, I can say that on average the top height setting for most lawn mowers is going to be no more than 4 inches.
So if you have to deal with taller grass anywhere from 4 and up to 8 inches, you can, in most cases, safely use your lawn mower.
- Start with having your lawn mower in the top height position;
- Make sure to place the bag. You want to bag all the cut grass to avoid any clumping;
- Go in one direction and try to overlap the different passes by a few inches. Don’t put on any lawn striping attachments; and
- After you are ready with the first go, you can try going lower, at which point you can also remove the bag and use the clippings as mulch if you like.
If you are not sure about the height of the grass at any point in time, feel free to use a measuring tape to find out how tall it is.
While you are doing the second cut, go in the opposite direction. For example, if you were going North-South during the first round, now go East-West.
The cut may not be the best possible, but it is more important to get the grass down to a proper height.
When you are done mowing, make sure to water the grass to provide it with some nutrients that will negate the stress of losing parts of its blades.
How Tall Is Too Tall?
Now, if you have to deal with grass that has been growing for a while and is about a foot tall or knee-high, you shouldn’t be using your lawn mower.
In that case, it is recommended to use a weed trimmer to trim the grass down to a more suitable height, typically about half of its current size.
After that, give the grass a few days to recover and repeat the trimming. You may end up repeating this step a few times, depending on how high the grass is.
When the grass is down to 6 – 8 inches, you can continue with your lawn mower as suggested above.
How Tall Should the Grass Be?
The best size for most kinds of grasses is between 2.5 to 3.5 inches – with the 3.5 inches being ideal for the summer months and the 2.5 is the more preferred height for the winter season.
The highest cutting setting for the majority of lawn mowers usually goes up to 3 to 4 inches – this is more than okay considering that most gardeners prefer to keep their lawn in the 2 to 3.5-inch range.
Here are some of the generally recommended grass heights (in inches):
| Bermuda Grass | 0.5 – 1.5 |
| Tall Fescue Grass | 3 – 4 |
| Centipede Grass | 1.5 – 2 |
| Zoysia Grass | 0.75 – 1.5 |
| Bluegrass | 2 – 3 |
| Perennial Ryegrass | 2 – 3 |
| Fine Fescue | 2.5 – 3.5 |
| St Augustine Grass | 3.5 – 4 |
The One-Third Rule for Cutting Grass
The one-third rule applies to cutting grass in general, but it is especially important when it comes down to cutting tall grass.
Sooner or later, everyone will have to deal with overgrown and very tall grass. One of the things that may be very tempting is to just cut it down to normal size in one go.
Many people consider this a big no-no.
Here’s why.
Although cutting the grass can stimulate its growth – cutting it aggressively like that can lead to the grass dying as a result of the unexpected loss of significant parts of the grass and loss of nutrients.
It can also introduce disease and fungus to it.
This is why when cutting grass, we always refer to the one-third rule, which states that we should not cut more than 1/3 of the total length of the grass at once.
In cases with overgrown and tall grass, you need to adjust accordingly. It may take a few days or weeks but start by cutting it down gradually. Don’t rush it all in one go.
Try to do that on sunny and clear days to stimulate grass growth and regeneration and reduce the chances of a disease spreading.
Generally speaking, you shouldn’t cut your grass aggressively for the reasons I’ve explained above. A few times a year probably won’t really harm your grass. However, if you are doing it often, it may cause some problems in the future.
If you are worried, I would suggest following the 1/3 rule and do the second cut after a few days. That being said, this is not a rule which is set in stone.
When Not to Cut Tall Grass
As you can see, there are a few concerns that you need to keep in mind when mowing tall grass.
However, there is one thing that may actually make you skip on cutting your tall grass for now.
I would not recommend cutting tall wet grass. If it has been raining for a while or there is heavy morning dew, I suggest waiting until the grass is dry.
Wet grass tends to bend over, making for very uneven cuts. Also, there is a high chance of the mower ripping off the blades of grass instead of cutting them.
And finally, wet grass tends to clump together in big patches that can clog your lawn mower and create more stress for the motor.
If you want to learn more about mowing wet grass, you can check out this article I wrote on the subject.
How Long Before the Grass Grows Too Tall for My Lawn Mower?
To look at the whole picture, first let’s take a look at the rates of grass growth. This will give us the necessary insight into what time frame we are going to be dealing with.
The actual rate will vary greatly depending on several factors:
- Type of grass;
- The total amount of sun hours;
- Time of the year;
- The total amount of precipitation and water; and
- Temperature and overall weather conditions;
On average, you can expect grass to grow anywhere from 2 to 6 inches every month.
So for the sake of the example, I will take some of the average numbers we have been working with so far.
Let’s say that you are cutting your grass at 2 inches, and your lawn mower has a top setting of 4 inches. How long is it going to be before the grass gets to 8 inches, at which point you will need to use a weed trimmer?
Given the numbers above, we can expect it to take about 30 to 90 days on average. Ideally, you shouldn’t allow your grass to grow unattended for more than 1 to 2 weeks, especially during the growth season.