U.S. Open greens crew mows Oakmont’s ‘unplayable’ rough in pro’s viral video. Here’s why

Even before 2025 U.S. Open week began, the long, thick, intimidating rough at Oakmont was getting a lot of attention. Defending champ Bryson DeChambeau recorded his shock at the long grass during a visit last week.

One look at Oakmont’s thick stuff, and the casual observer might think it hasn’t been mowed in weeks. But on Monday evening, one U.S. Open competitor recorded a strange and mesmerizing sight: an army of U.S. Open maintenance crew members cutting the rough all over the course.

But all was not as it seemed. Here’s what you need to know.

U.S. Open pro’s viral Oakmont mowing video

After a long day of practice rounds, four-time PGA Tour winner Jhonattan Vegas was walking the course Monday evening when he came upon a captivating scene. In front of him marched a group of at least 20 maintenance crew members, each operating a push mower.

The workers, all dressed in matching gray hats, gray shirts, and khaki pants, formed a synchronized mowing ballet, carefully cutting each patch of the rough areas that needed a trim.

Check out Vegas’ video below.

But this scene was not a result of the USGA feeling pressure from complaints about the rough being too long. As Vegas pointed out in his post, “Good news guys, they are cutting the rough but, it’s still unplayable. Have fun.”

Instead, regular mowing of the rough is crucial to making Oakmont’s rough so thick.

How Oakmont’s rough got so thick for U.S. Open

But how do the U.S. Open and Oakmont maintenance staffs get the rough to be so thick in the first place?

Fortunately, our GOLF team got the answer to that question from the leaders of the maintenance staff at Oakmont.

As Max Claassen, the director of agronomy at Oakmont, explains in the video below, you can’t just let short rough grow several inches and call it a day. If you do that, the rough would become long and floppy, kind of like if you let your yard go too long between cuttings.

“On Oakmont, we went from normally cutting it at 2.25 inches, to trying to get to a uniform 5-inch standard of rough for the [U.S. Open] championship,” Claassen told GOLF. “You have to slowly increase your height of cut … if you just let 2.25 inch rough grow to 5 inches, you’re going to have no structure to that plant. It’s going to lay over, and you’re going to have fly lies and it’s really not going to be penal. At the end of the day, you want the ball to sit down in it, that’s the real challenge.”

To get the rough to grow long and thick, they have to gradually increase the height of the rough by a half inch at a time.

“Say you raise by a half inch and you cut four times like that, the crown of the plant is actually raising, and it’s going to get acclimated to cutting at that height. Then you go up again. A lot goes into it.”

And that explains the mowing procedure captured by Vegas Monday night. Rather than dramatically lowering the height of the rough, the maintenance crew was mowing a very small amount of grass off the top. The reason for doing so is not to make the rough easier to play out of, but to make it even harder.

For a more thorough review of the work that goes into transforming Oakmont from a regular club into an Open venue, check our GOLF video below, or watch it on YouTube here.