Even experienced homeowners who have mowed their lawns for years may ask themselves “What height should I cut my grass for best results and a healthy lawn?“
Many folks, especially those new to maintaining a lawn, may not think much about their grass height. Most people mow their lawn every weekend, or when the grass looks too long. Perhaps you have a landscaping team that comes every other week and you don’t put much thought into your lawn health.
However, the height of your grass is actually an important factor for lawn care, and it can also play a significant role on the environmental benefits associated with green space.
In this article I’ll tell you the ideal height for mowing your grass, how to determine that height for your lawn, and I’ll also explain why getting the height of your lawn’s grass right matters.
Let’s get started!
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The Anatomy of Grass
For ease of reference, it’s important to define the anatomy of grass.
Grass grows from tiny seeds, which sprout or germinate in the soil and grow both above and below the surface of the soil.
The part that grows above the surface is called the blade, and the part that grows below and deeper into the ground is the root.
Different species or types of grass can have different looking blades – perhaps a more broad-leaf blade or a narrower blade. These differences make certain grasses better in varying conditions (eg. full sun, full shade, part sun, etc). However, aside from ornamental grasses in a garden that grow quite tall, regular grass on your lawn should ideally be kept around 2.5-3 inches tall at minimum, regardless of what type it is.
The truth is that most people mow their lawn’s grass too short, which can harm or kill the grasses that your kids and pets play on, and cost you money when you have to fix the problems that come from mowing your lawn too short.
Grass Height by The Numbers
Answered: What Height Should I Cut My Grass?
A majority of sources suggest keeping your lawn about two and a half inches tall through most of the year.
The exception to this is in the spring when a slightly longer lawn – three inches or so – can help prevent weeds and crabgrass from growing by crowding them out.
No matter how long you prefer to keep your lawn, you should only ever be removing the top third of the grass blade. This minor trim stimulates growth without putting too much stress on the grass and keeps the blades large enough to prevent weeds from taking hold.
Even more than how tall your grass should be, it is important not to trim it below two inches tall.
Cutting a lawn too short is often referred to as “scalping” and can provide opportunities for weeds to seed and grow.
A short lawn is a stressed lawn that is exposed to more heat and sunlight. When cut too short, the grass also puts more effort into growing the blade as opposed to deepening the roots. This creates a fragile system where the grass struggles to get the nutrients it needs from the soil and can be easily pulled up or damaged.
TIP: Instead of having to measure your grass to know when it’s time to mow, mark a spot you can check. This could be a mark on the side of your mower that you can reference in the grass, or perhaps even in an inconspicuous spot on your deck or fence that you could peak at periodically.
Adjusting Your Mower
Now that you’ve answered the question that brought you here: “What height should I cut my grass?”, it’s time to set your mower’s height appropriately.
The height of your lawn mower can be adjusted to ensure that you are not scalping your lawn. Adjusting the height can be a bit different on various types of mowers, so it is best to look at your owner’s manual or check your lawn mower model online for instructions.
Lawn tractors or zero turn mowers usually have a mechanical or hydraulic lever that raises and lowers the mowing deck. Push mowers often have to be manually raised or lowered at each of their four wheels.
By raising the height of the mower – either the deck or the blade height – you can prevent cutting the grass too short.
A Sharp Blade Matters
Along with setting the mower at the right height, it is important to ensure that your blade is kept sharp.
Sharpening your existing blade twice per year is a good rule of thumb for many homeowners. But how often you use your mower will dictate how frequently you need to sharpen your blade. Nicole Forsyth, a certified horticulturist and member of our expert panel, shares that “commercial businesses usually sharpen theirs 2x a week.”
If you’re handy enough, blades can be sharpened at home using a file, grindstone, or a bench grinder. You can also purchase replacement blades online or at a store that carries your brand of mower.
A very important note: remember to remove the spark plug before ever doing any kind of maintenance on your lawn mower to prevent it from accidentally starting!
Setting a Mowing Schedule That Works for Your Lawn
Mowing your lawn on a schedule, for example every Saturday, is actually not the best practice, even though that’s how most of us do it because we work, have soccer practices to attend, etc.
The reality is that grass growth is heavily dependent on the weather.
Grass will experience a growth spurt after a period of rain. And it may not grow as much if there is not enough water. This is why mowing on a schedule is often counter-intuitive.
I recommend paying attention to grass height, and allowing that to dictate when you mow.
This may mean that sometimes you are mowing the lawn weekly and sometimes you may go a few weeks without needing to mow.
Over time, this will transform your lawn and improve its health. You’ll be amazed by how doing this for a season can improve your grass.
Your Landscaping Company’s Schedule Matters Too
For this same reason, if you decide to hire a landscaping company to help with maintenance check what their methods for scheduling work are. Ensure that they are not scalping your lawn by just showing up and mowing regardless of grass height.
There are many landscaping companies that have been well educated via landscape architecture and design courses and degrees. But there are just as many landscaping companies that don’t necessarily have the same knowledge.
You pay your lawn company when they mow, so it makes sense that they will want to mow your lawn more often. This may not be good for your grass.
If you have newly seeded grass, it is important to give it enough time to get established before mowing. It is best to wait until it is 2.5 – 3 inches tall before cutting it.
If your new grass is from sod instead of seed, then it is important to wait two to three weeks to allow it to properly root into the ground before mowing it as well.
Ideal Lawn Mowing Conditions
The best time to mow the lawn is in the early evening when there hasn’t been recent rainfall and the lawn is dry. Cutting the grass in the morning might mean that dew is still on the grass. Wet grass can clog your mower or lead to uneven cuts.
Mowing before the hottest or sunniest part of the day also leaves the grass vulnerable to extra stress.
Trimming your grass is already a stressor in itself. Thus, early evening allows the grass lots of time to recover overnight.
Mowing direction is also surprisingly important. Following the same route with your mower each time you cut the grass can lead to the grass leaning that way permanently, which can make your lawn look awkward and uneven.
I recommend that you change up your pattern at least every other mow. This will ensure that the grass grows straight and tall.
While clippings can seem a bit unsightly on a lawn, they are actually very good for plant health. They prevent weeds from popping up and provide important nitrogen and other nutrients to the newly cut grass. Nicole Forsyth suggests that “you can ‘double cut’ the lawn to chop them up more and change the pattern of the mow” if you don’t love how they look at first.
If you do still decide to bag the clippings, consider composting them and then using the compost to fertilize your own yard once every year.
Environmental Benefits Associated with Lawn Height
You may not think of this, but lawn health and environmental health have direct links to lawn height.
Letting your lawn grow taller is not only good for the grass itself and the root system, but it also supports the ecosystem in your yard. Longer grass offers the following benefits:
- Effectively filters toxins from water runoff after heavy rainfall or watering.
- Provides important temperature moderation by absorbing the heat from the sun for photosynthesis; grassy areas are 5-7 degrees Celsius cooler.
- The cooling effect that it provides also means less strain on energy systems to cool surroundings.
- Supports healthy honey bee colonies, which are crucial to agriculture and the environment at large.
Quid Pro Grow
Maintaining a beautiful lawn isn’t as much work as one might think once it has been properly established.
Deep roots that form by letting grass grow a bit longer will help sustain a healthy lawn. It’s actually better to err on the side of less is more; don’t cut too frequently in order to keep your lawn in good shape.
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