Flail Mower Vs. Rotary Mower Attachments: What's The Difference?

Ryan Womeldorf
by Ryan Womeldorf

There is something of a misconception that all mower attachments are the same. The fact of the matter is that there is a huge array of attachments that can be used with tractors, skid-steers, excavators, and wheel loaders. All of which are designed to work optimally in certain situations.

When finding the right cutting attachment, there are two, in particular, that stand out. What is the difference between rotary and flail mowers? Rotary mowers use horizontal blades that can cut thicker brush but are less accurate. They are better for bigger plots of brush. Flail mowers use cutting knives that provide a much cleaner, manicured cut. You would use a flail motor for achieving a more accurate cut.

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The Main Differences Between a Flail Mower and Rotary Mower

The first step to choosing the right attachment is understanding what each one is capable of doing. The biggest mistake made is assuming that attachments are interchangeable when that couldn’t be further from the truth.

Each attachment has its own specific use and application. That is just as true for rotary and flail mowers as it is for any other attachment type. Here are the main differences between the two.

Blade Type

If you want to find the biggest differences between flail mowers and rotary mowers, start with the blade. Rotary mowers make use of a horizontal blade. These blades are much more versatile than flail mower blades, capable of cutting some of the thickest brush around. The rotary blades won’t give you a very manicured cut, though.

Flail mower blades, on the other hand, are longer and knife-like. They are not built to handle the amount of brush that the rotary mower can handle. You wouldn’t want to use a flail mower for hacking through major overgrowth, for instance.


Their uses are quite different as well. Using one to do the others may work but won’t deliver the kind of results that you are looking for.

Rotary mowers are meant for removing a lot of brush and debris in short order. If you are working through massive overgrowth and brush, the rotary mower would be the best bet to get it all cleared. You can then come in with something more precise if you wanted a more manicured look.

You would use a flail mower for more precise mowing. Because of the blade design, it makes cleaner cuts than the rotary mower would. Likewise, you would not want to use this mower for clearing brush as it is not meant for heavy-duty use.

Power and Cut

Finally, we are going to look at how both mowers are powered and the way that their blades ultimately cut. The rotary mower is hydraulically powered. It makes use of thick, large blades that aren’t terribly sharp to cut through large brush in short order.

Flail mowers, meanwhile, can be powered either hydraulically or by PTO drive. The cut type is also driven by either T- or Y-shaped spinning blades. The sharpness, especially in contrast to rotary mowers, provides the accurate cut described above.

Basics About They Work

Now that we know what separates the two and makes them very different, let’s learn about how each of them works. Both mowers work in stark contrast to one another, coming to different results in much different ways.

Flail Mowers

Flail mowers make use of knives that are attached to an elongated shaft. These are generally used to cut down grass that has already been brought down to a standard high that a finished, manicured look can be applied.

The blades, in T- or Y-shape, spin around the shaft. As they move, they clear grass as the shaft runs parallel over that given surface. The shredded remains are then distributed over the width of the mower, being ejected as the mower moves onward.

Rotary Mowers

Rotary mowers are also known as brush hogs. These are generally designed in a similar manner to your household lawnmower, just a lot bigger. When you need huge swatches of brush or overgrown grass cut in short order, you would go with a rotary mower.

They slice through the taller grass by essentially sucking it upward and then cutting it using those horizontally spinning blades. The main difference between a rotary and a household mower is that the blades on rotary mowers are not sharp.

Rotary mowers make use of heavy-duty use blades that are thick and large. Since they are rough, they deliver more power than they do accuracy.

Size of the Cut

Another major difference between the two mower types is the cutting width. There is also the factor cut sped as well as any flying debris that may be present.

Flail Mowers

Flail mowers, since they are meant to cut larger swatches of heavy brush, have wide cutting widths. They can range from 38” up to 102” in width. There are even some mowers that have attachments that can increase the width to up to 200”.

The caveat here is that flail mowers cut at a much lower rate of speed. The mower is heavier and takes a lot more time to cut through the brush. That is partially why the cuts are more accurate than their counterpart.

Rotary Mower

Rotary cutters have a much shorter width but cover a pretty good amount of surface area thanks to a greater depth. They also move at much higher rates of speed, which aids in a cutting through brush at an accelerated rate.

The downside here is that they are not only less flexible, but more easily damaged by landscape debris. Getting a rock in your flail mower might not cause much damage but there is the potential for damage. They also kick up a lot more debris than flail mowers do.

Type of Project(s)

When you are determining which type of mower would suit you best, you must first consider the project at hand. Because their designs are so different, both have some flexibility to a certain extent before they become more of a niche cut.

Flail Mowers

Because of their accuracy, flail mowers are ideal for spaces that need to be manicured or cropped. Large grassy areas that require clean cuts are great since the knives also chop up and mulch the plant life, providing benefit as it mows. That means returning nutrients to the ground to provide a better overall growth.

Flail mowers can cut through brush but they take longer to not only catch but mulch the brush. If you have trees and heavy brush, though, it is not ideal to use a flail mower to get the job done. There are some that are specifically designed to tackle such projects though, so look into that as a possibility.

Find out how to dethatch a lawn with a mower attachment.

Rotary Mowers

Generally speaking, you would want a rotary mower for areas that are heavy with grass, brush, and trees that have become overgrown. Since the blades are thick, they are good for taking down dense vegetation and even saplings easily.

Rotary mowers can be used on grass but don’t expect a clean cut as you go. And be aware of flying debris. Rotary mowers kick up a lot of debris, which can be potentially hazardous depending on the location. It is always a good idea to wear proper safety equipment when using a rotary mower. You never know when something might come flying in your direction.

High or Standard Flow

One of the final factors to consider when comparing rotary and flail mowers side by side is the flow rate. You also want to keep in mind the horsepower of the equipment that you will attach your cutter to, be it wheel loader, excavator, tractor, or something else.

The needs of the machine will dictate the type of attachment, whether you own it or need to purchase a new one. Rotary cutters tend to be much more versatile as a rule of thumb. They come with motor options to match both standard and high-flow machines.

Flail mowers tend to be a lot more specialized when it comes to the two. The majority of high-flow machines typically require running a flail mower instead of a rotary, for instance. Check out the 5 best lawnmowers for wet grass.

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Which is the Best Option?

There is no simple answer to which option is better between a rotary mower and a flail mower. It ultimately comes down to the job type as both are better suited for one application versus the other.

For heavier brush that needs to be cleared away in short order, the right choice is a rotary mower. The heavy-duty blades can knock down dense vegetation and saplings with little to no issue. The attachments are also lighter and faster, covering a lot more ground in a shorter period of time.

For more precise cuts, the flail mower is the better option. It can provide a manicured look that rotary mowers just can’t hope to match. In some circumstances, you can also use flail mowers to clear brush, though it all depends. For really thick and dense brush, the rotary mower would be the better option. It depends on the specifications of the flail mower that you are considering.

Ryan Womeldorf
Ryan Womeldorf

Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.

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