What Height to Cut Grass – The Right Setting for Your Lawnmower

What kind of ‘mower’ are you?

A: The kind that allows the lawn to grow until it becomes its own self-sustaining ecosystem, with complaints from the neighbors that your lions are upsetting their poodles?

B: The set-your-watch kind that scalps the grass back to nothing at the same time each week, come hell or high water?

C: The kind who mows – somewhat reluctantly – only when it looks untidy, or when life permits?

D: Your mowing schedule and cutting height changes depending on the time of year and type of grass you have?

If you answered ‘D’ – congratulations! You’re on your way to a healthy, lush, green lawn. But keep reading to find out if you’re doing it right!

For everyone else, you could do with a few pointers on what height to cut grass, so read on for some top tips on lawn maintenance.

Give Me the Short Answer – I Have Gardening to Do!

If you just want to know how high to mow grass – here’s the “too long, didn’t read” version for anyone in a rush:

The answer, like most gardening practices, depends on a number of factors.

mowing a green lawn

Correct mowing height varies depending on the season, and it also varies depending on the type of grass species you have in your yard.

However, the generally accepted rule-of-thumb is to keep your grass 2-4-inches in height for cool-season types, and 1-3 inches for warm-season species.

There is, of course, much more to it than that – so don’t touch that dial just yet!

Grass Mowing Height – Does it Matter?

It’s a valid enough question – how much does the height you mow actually matter to the overall health, look, and feel of the grass?

If you want the best lawn possible, then grass-cutting height is just as important as all the other steps in a full lawn care schedule. And you can follow that link for our detailed month-by-month guide.

Sticking to the recommended mowing height for your grass type is going to make the difference between an average lawn and a noticeably manicured patch of vibrant green to be proud of.

And during the summer months it’s particularly important that you don’t over-mow, or scalp the grass too close, in order to help your lawn survive through the heat.

Grass that’s cut too short will become stressed, and won’t be able to develop a deep root system. It can also open the backdoor for undesirables to take over, like these six most common lawn weeds.

Leave your grass too long, however, and you can encourage pests and disease, as well as an unsightly yard in general. This in-depth look at how to cut tall grass will tell you more.

So, while you don’t necessarily need to take a tape measure out there (although many dedicated lawn care enthusiasts certainly do), you should at least try to keep to the mowing height guidelines each season.

hand on green grass

Read on to find out exactly what they are.

Mowing Height – Through the Seasons

The best height to mow grass varies from season to season, and it’s not “one-height-fits-all.”

Many/most homeowners will never even touch their lawnmower height adjustment – and that’s fine if you want an average-looking lawn, and/or lawn maintenance isn’t a priority for you.

As an example, I’m on a street with, maybe, 18 properties, and I’d say I was the only one practicing any kind of lawn care schedule, over and above a regular trim during the growing season.

But for anyone interested in proper lawn care, then listen up. Or, rather, read up:

In hot conditions – such as through the summer months – allow your grass to grow a little taller than normal. This is also applicable in times of drought, should it occur at any time of year.

Speaking of, here’s a full guide to watering your lawn – which might come in handy when things are a little dry.

But you should always take care when mowing wet grass, too. AKA – don’t do it. Not only can it increase the risk of accident, but you’re not going to get that razor-sharp cut you would if the grass were dry.

If you absolutely have to give your lawn a trim when it’s damp, follow the link above for some expert advice on how to manage it safely.

Warm-season grass should be trimmed shorter during the spring, and cool-season grasses can be trimmed shorter in the fall.

The final mow of the season should be a little lower than usual to help prevent snow mold in the winter – if you happen to live in an area that is blanketed with the white stuff (which is just about everywhere, these days).

But when in doubt, the professionals always recommend mowing taller in the summer, and a little lower in the spring and fall.

person mowing lawn in summer

Seasons aside, the type of grass you have in your yard will also have some influence on your lawnmower cutting height. Let’s take a look, so you can figure out what you’ve got.

Mowing Height – Types of Grass

Just as the mowing height varies depending on the season, so it does depending on the type of grass in your yard.

Rather than go into the scientific explanation for this (different species have different needs, basically), here’s an at-a-glance table, so you can see what height to mow the particular grass you have.

Cool Season Grass Recommended Mowing Heights

  • Perennial Ryegrass – 1.5-2.5-inches.
  • Kentucky Bluegrass – 2.5 to 3-inches.
  • Tall Fescue – 2-3-inches.
  • Fine Fescue – 3-4-inches.

Warm Season Grass Recommended Mowing Heights

  • Bermuda Grass – 1-1.5-inches.
  • St Augustine – 2-3-inches.
  • Zoysia – 1-1.5-inches.
  • Centipede – 1-2-inches.

However, it’s not enough that you know how high to mow your grass, but you should also learn the height at which the grass needs to be cut at!

The following table shows you when the mower needs to come out of the shed – when your species of grass reaches that particular height.

Cool Season Grass – When to Mow

  • Perennial Ryegrass – 2-4-inches.
  • Kentucky Bluegrass – 3-4-inches.
  • Tall Fescue – 3-5-inches.
  • Fine Fescue – 3-4-inches.

Warm Season Grass – When to Mow

  • Bermuda Grass – 1.5-2-inches.
  • St Augustine – 3-4.5-inches.
  • Zoysia – 1.5-2-inches.
  • Centipede – 2-3-inches.

I recognize that’s all a little specific, and you might not want to bother with the exact measurements. If that’s the case, then you can follow this general rule of thumb:

Keep cool-season grasses around 2-4-inches in height, and maintain warm-season grasses at around 1-3-inches.

And if you’re still unsure as to the type of grass you have, you can check out the video below – or head over to this article on the different types of grass seed – which can also help you with overseeding.

Keep reading for an easy way to remember how much you need to trim your grass.

The 1/3 Mowing Rule

Another way you can determine the height you should set your lawnmower at, is to never trim more than 1/3 of the grass blade each time.

I’m not very good at math, so let’s keep this simple.

For example, if you happen to have a lawn that mostly consists of Kentucky Bluegrass, you wait until the blades are at least three inches in height, then you only lop off the top third – which is one inch.

Voilà – your lawn has been mowed to an excellent level for that particular species.

Top tip – for fine-tuning your lawn height, (or for when trimming new and delicate grass growth), I highly recommend having a reel mower in your tool collection. This article on the reel mower benefits will tell you more.

This leads us nicely onto another factor in grass cutting height – the lawnmower itself.

Mowing Height – Lawnmower Tips

One of the most important tools in your lawn care arsenal is going to be your lawnmower, so it helps to add in a few extra tips and tricks for achieving the perfect cut.

And you can follow the link above for a full list of everything else you need for successful lawn maintenance.

First, you should make sure you’re using the right type of lawnmower for your yard. It may sound silly, but there are folks out there who regularly try to battle Mother Nature with improper gear.

Each summer, I watch a guy on my street attempt to cut his giant lawn with a cordless lawnmower that only has a 40V battery! (Perhaps it’s time I said something.)

He might be better off checking out this review of the best commercial zero-turn lawnmowers. You can also go here for some budget-friendly lawnmower options if a zero-turn is a little excessive!

Always make sure the lawnmower blade is sharp. There are so many homeowners who neglect this, and then wonder why it takes forever to mow the lawn, and/or the end result isn’t aesthetically pleasing.

Pick yourself up a good lawnmower blade sharpener at that link, and get into the habit of practicing annual lawnmower upkeep with the help of our full checklist.

Your mower will last longer, the grass will cut cleaner, and your lawn will look better. It’s a win-win-win.

crabgrass in lawn

Blades should also be free from dents, dings, corrosion, damage – or anything else that is going to cause it to perform poorly. Sometimes, you will just need to cut your losses and replace the blade.

Fertilizing, Overseeding, Dethatching, Aerating…and Mowing

Finally, it’s worth including a few extra notes on the relationship mowing has to several other key lawn care practices. When should it be done during fertilization, overseeding, dethatching, and aerating?

We’ve written several articles on each (the links to which are included, below), but here’s a general guide to the order of things for your convenience:

  • Dethatch.
  • Mow.
  • Aerate.
  • Overseed (if required).
  • Fertilize.

If you’re not using a weed and feed, weed treatment should be done before fertilizing. Does fertilizer kill weeds? Follow that link to find out.

Go here for top tips on dethatching, follow this link for how to mow your lawn properly, head over to this article for a full guide to aeration, and go here for advice on overseeding and how to do it.

Last, but by no means least, this article on the different types of fertilizer will tell you what you need for your lawn, and go here to learn how and when to lay fertilizer down in your garden.

FAQ

Should I mow my grass once a week?

No. For the best possible lawn, you can’t rigidly adhere to a set mowing schedule – because you’re going to get different results depending on growing conditions, environmental factors, and more.

Instead, take the time to examine your grass, and cut only when necessary, and when it reaches the heights recommended for each species in the article above.

Do I need to mow more after I fertilize?

Yes. The chances are, if you’ve applied a good-quality fertilizer that’s right for your soil and grass type, (and you’ve applied it correctly), you’re going to see a growth spurt across your lawn.

And that’s what you want, right?!

As such, you will need to mow more often – but wait at least 24-48 hours after fertilizing for the first mow, and in any areas you’ve laid down new seed, increase those numbers to six to eight weeks.

Should I mulch or bag my grass clippings?

Great question! I would say that you should definitely be mulching your clippings – through the summer at the very least.

Don’t forget, if you’re sticking to the 1/3-rule, there shouldn’t be a lot of material coming off anyway, and that’s going to help shade and compost your lawn over time.

This article on why you should mulch your grass clippings will tell you everything you need to know.

How do you adjust the height of a lawnmower?

It’s a valid question – as different mowers have different controls, and sometimes, it’s not always clear.

For most four-wheeled, walk-behind mowers, there should be a lever located close to the rear set of wheels. This level can adjust the cutting deck at increment heights – the amount of which will depend on the model.

Riding lawnmowers – including zero-turn models – will have a lever located somewhere within reach of the seating position on the chassis.

Top tip – when in doubt, mow a small, inconspicuous area of grass to test if the lawnmower is at a satisfactory height for trimming the rest of the yard.

Summary

Understanding what height to cut grass is critical if you want to achieve a healthy, lush, green lawn in your yard – but it’s something that’s often overlooked.

I hope this article has helped you choose the right mower settings for your needs – and the needs of your grass.

Let me know if you have any lawn height cutting tips you’d like to share with our readers. We’re always keen to learn new things!

Stay safe out there, and happy mowing!

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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