Are there benefits to changing the direction you mow a lawn?

Question

This is one of those ancient bits of "wisdom" I vaguely recall from my childhood; and now that I have a lawn which seems quite happily established, I'm looking into keeping it that way. So, I want to know if there's any truth to it.

Supposedly, each time you mow your lawn, you should change the direction you mow. For example, travel north/south one mowing, then east/west the next mowing.

It's obvious if you look at a freshly mown lawn which direction the mower traveled, which I think lends this idea its believability. But I can't honestly think of any benefit to the plants. After a day or two they're all still happily growing "up" after all. And with a motorized spinning blade, I don't see how you could say that a blade of grass was cut "this way," anyway.

So, is there something I'm missing? Is there some benefit to the plants? Or is there some quirk of reel mowers which made it true in the past; and if so, is it still true?

Answer 1

I suspect the guidance came from a time of reel mowers, which do actually push the blades of grass over in the same direction. (I use a reel mower to maintain our acre and a half.) As you've pointed out, with a rotary mower there is a lot more randomness involved.

That said, if you mowed your lawn with the exact same path every time, you would probably always miss the same little triangle "downstream" of a particular tree. If there's a bump, the grass "before" the bump would always be a little too short and the grass "after" it always a little too long. If you always mowed parallel to a path the grass next to the path might not get cut, but if you went back and forth across the path it would.

Probably you can solve most of that with a trimmer. The advice is certainly about the last little bit of perfection rather than overall lawn health. But it doesn't take any longer for you to mix it up once in a while, or to follow a pattern where you go east-west one time, north-south the next, west-east the next and so on. It probably does reduce the amount of trimmer work you need to do and give you a little more uniformity.

Answer 2

Theory says that changing up the mowing pattern will keep the grass from always bending in the same direction.

Another reason I've heard stated is that it keeps wheel ruts from forming.

I might buy the latter but the former's probably not a real problem. Grass tends to want to grow where it wants to grow, generally upward towards the sun. Maybe running the same, exact route each week might develop ruts but I've never see it happen here except when I've run one through really wet ground, which I try not to do.

I run mowers (push, riding and tractors) all over my farm and only mix up the cutting direction when I notice that I'm not getting a patch of grass cut well from a given angle - for instance my drain field area tends to cut better when I go back and run along the lines rather than across them. That's because the ground is uneven.

I think it is mostly an aesthetic thing. I don't see the direction really affecting the lawn one bit. A neighbor mixes it up each week and his lawn looks nice but I doubt there's any real benefit to the grass itself over cutting the same pattern.

I'm assuming, of course that one is cutting per general guidance - no more than 1/3 cut off and stuff like that.

Answer 3

@Kate Gregory has a good point about reel mowers, but a rotational mower won't have the same problems.

I don't buy the "direction of cut" argument, and here's why:

The blades aren't moving the same direction you are. If you compare the mower blade to a helicopter, the blade is retreating faster than you're moving forward. Depending on the location under the mower, the blade direction is moving forward, backward, left, or right. Do you make the EXACT same number of passes down to the inch every time you mow your yard? If not, then the grass is getting cut in different directions every time anyway. Even as you move forward, the direction of the blade changes with respect to a static point on the ground. The point centered with respect to your mower first gets hit from the left by the blade, and as you continue walking forward gets hit from the right side after it crosses the center point of the mower.

As for wheel ruts forming, it may be possible. Although I always have a few inches of variability with every pass, so I don't put the wheels in the same place every time I mow.

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Answer 4

That ancient advice was valid once, in the days when everyone used cylinder mowers with a small roller on the back and wanted a striped lawn. If you didn't vary the cut in the way you describe, over time, a grooved or ridged effect would appear between each mown strip, in other words, a raised edge, from where the roller and the blades continually run, so changing the direction avoided that problem. Irrelevant with most modern mowers.

Answer 5

And with a motorized spinning blade, I don't see how you could say that a blade of grass was cut "this way," anyway.

A couple of other people made reference to the spinning blade creating forces in multiple directions so it doesn't matter but that's not relevant. The only force that matters is the last force applied before the blade is clear of the mower deck. That will be the direction the grass will lay.

Imagine you had an orbital polisher . You are polishing your car with a fairly coarse compound doing one horizontal stripe left to right and then just above it you are coming back from right to left.

The bottom stripe will have noticeable swirl marks swirling up and the second row will have swirl marks swirling down. Except for the end where you stopped that strip which will have the front swirl marks match up with the front of the polisher.

In addition to that when you're always walking along the same path you're going to be compacting the soil where you're walking and where the tires are rolling. I have a section of my lawn that's frequently crossed by foot because there should have been a pathway there but isn't. Over the years it developed a noticeable depression. Soil will compact worse when it's wet which is one of the reasons you shouldn't mow your lawn when the soil is very moist.

Different varieties of grass will also be a factor. I noticed the fine bladed grass commonly used in shady mixes retain the swirl direction more.

The length of the grass blade seems to also be a factor. In the summer when I have my mower set to cut at it's highest setting it seems even more important to vary the mowing directions.

Over time the grass can pick up a lean in one direction or the other.

The advice is still applicable with rotary mowers and is worth following.

Answer 6

Think of it as wind blowing plants or trees in the same direction all the time. They seem to grow in that direction. Calm your hair in a different direction. I kind of like to think it helps because it's almost like you're weaving the grass the blades together like a carpet. I've used several patterns vertically corners from left to right straight line one way straight line the other way and Square box cut. It also helps not to cut the grass below 3 inches.. it looks strange at first but like pruning a tree it's not pretty after pruning but it does go back prettier than ever I hope this help I love my grass so do the neighbors. Deep plush carpet that Springs back with each step

Answer 7

When you mow your lawn back and forth you see the different lay of the grass and the ruts where the wheels flatten the grass, if you mow in different directions the tracks left in the lawn even out to give you a smoother looking lawn.

Answer 8

Simple Answer, Yes. If you mow the same direction each time you tend to roll the mower's wheels over the same lines time and again. The results are lines from suffocated and dead grass. You can avoid by using different starting points but that's not very pleasing to the eyes because you'll end up with two narrow end stripes. Yes, change directions!

Answer 9

Having recently bought a mower with a roller (a Hayter Harrier 48) I can absolutely now see the relevance in not mowing the same direction every time! It’s not about which way the blades spin, it’s more about which way the roller bends the grass! That being said, prior to my new mower, I’ve never had a roller, just a mountfield rotary mower! I can say tho that alternating cuts each time (north to south, then east to west etc) does make the grass healthier and stand more upright for sure! Just try it! Hopefully it work for you too!

Answer 10

My thinking is: If the ground is soft, mowing in different directions will bend the grass enough to allow the soft ground to move allowing to aerate your lawn.