Mowing the lawn is a simple job, right?
After all, your 10 year-old son would probably do it for a few dollars.
This is true to a point, but did you know that height matters? Like, really matters?
The length of your grass, and the amount that you remove when you mow, can seriously impact the health of your lawn.
This article will explain how grass mowing height should vary through the year and according to what grass species you have in your lawn.
- Give Me the Short Answer – I Have Gardening to Do!
- Grass Mowing Height – Does it Matter?
- Mowing Height – Through the Seasons
- Mowing Height – Types of Grass
- The 1/3 Mowing Rule
- Mowing Height – Lawnmower Tips
- Fertilizing, Overseeding, Dethatching, Aerating…and Mowing
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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.
Correct mowing height varies depending on the season, and it also varies depending on the type of grass species you have in your yard.
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.
During the summer months it’s particularly important that you don’t mow too short, in order to help your lawn survive the heat. It’s also helpful to leave your lawn a little longer when your region is experiencing heavy rain.
Grass that has been cut too short will become stressed as it won’t have been able to develop a deep root system. It can also open the gate to other non-grass species, like these six most common lawn weeds.
On the other hand, leaving your grass too long all the time can encourage other pests and diseases, can result in a patchy lawn, as well as likely irking the neighbors.
So, while you don’t necessarily need to take a tape measure to your lawn, you should at least try to keep to the mowing height guidelines for each season.
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.”
Most homeowners will never vary their lawnmower height – and that’s fine if you’re not aiming for a perfectly manicured lawn.
But for anyone interested in maximizing lawn health, it’s worth understanding how varying grass height through the year can help to achieve a lush, green lawn of enviable quality.
In hot conditions – such as through the summer months – allow your grass to grow a little longer than normal. This is also applicable in times of drought, at any time of year.
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.
The Rest of the Year
When it comes to the other seasons, it’s important to know what grass species you have, namely whether they are warm season or cool season species.
Warm-season grass can be trimmed shorter during the spring, and cool-season grasses can be trimmed shorter in the fall. This is because these grasses are in their active growing phases during that time; conditions are good and the grass can handle a shorter crop.
If you live somewhere prone to heavy snowfall that will sit on the lawn for the duration of winter, the final mow of fall should be shorter still. This will help to prevent snow mold in the winter and generally help the lawn survive until spring.
But when in doubt, the professionals always recommend mowing taller in the summer, and a little lower in the spring and fall.
Mowing Height – Types of Grass
As mentioned above, the type of grass you have will factor into mowing height decisions.
Different grasses are best suited to different mowing heights.
I’ve summarized the heights here to make it easy for you.
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 also important to remember that that old wives’ tale about never removing more than a third of the grass’s height at once is true!
The middle third of the grass blade is where all the magic of photosynthesis happens. Remove this by cutting too short and you are literally starving your grass of its life-giving properties.
It is best practice to gradually shorten the length of your lawn with multiple mows over time, as described in this article.
But, to avoid having to go through that process, give your grass a trim (of no more than a third of its total height!) according to the lengths listed here:
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 pretty 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. Leaning on the slightly longer side is almost always better for lawn health.
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.
The 1/3 Mowing Rule
If all these inches are a little overwhelming, you can always go back to the rule of thirds, as mentioned earlier.
Once your lawn is starting to look untidy, provided it’s not the heat of summer or the depths of a very wet month (both of which call for longer grass), roughly estimate how much you would need to remove to take a little less than a third off the top.
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. 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.
Get into the habit of practicing annual lawnmower upkeep with the help of our full checklist.
Your mower will last longer, the grass will get a cleaner cut, and your lawn will look better. It’s a win-win-win.
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 your grass be mowed when you also need to fertilize, overseed, dethatch, and aerate?
I’ve written several articles on each (links included below), but here’s a general guide to the order of things for your convenience:
- Overseed (if required).
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.
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 lever 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.
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!