In short, if you are cutting cool season grasses such as fescue, you will need to sharpen your lawn mower blades after mowing a 1/4 acre 30 to 90 times.
If you are cutting warm season grasses such as Bermudagrass or Zoysia, you will need to sharpen your lawn mower blades after mowing a 1/4 acre 5 to 15 times.
It is a great question with lots of caveats though.
Many other people are wondering how often they should sharpen their lawn mower blades too. Lets go into more detail on when you should sharpen your lawn mower blades. Learn more about mower blades by reading my other articles linked at the end of this one.
You should sharpen your mower blades when they are dull!
I assumed you didn't want this answer so I gave you some measurable guidelines first!
But, at the end of the day you really only need to sharpen your lawn mower blades when they have gotten dull enough that they do not put a "flush-cut" the grass blades as you mow.
If your lawn mower blades are sharp, they will transfer a clean cut to the grass blades as you mow your lawn.
If your lawn mower blades are dull, they will tear the grass blades as you mow creating 'hairy' tips on the grass blades.
Why does my recommendation on how often to sharpen mower blades have such a range?
I started by stating mower blades cutting cool-season grass should be sharpened every 30-90 mows of a 1/4 acre lot and warm-season grass should be sharpened every 5-15 mows of a 1/4 acre lot.
There are a couple of reasons and here they are.
Sharpening Blades When Mowing Cool Season Grasses
Cool season grasses are not as stiff as warm season grasses. If you are 'just cutting grass,' then naturally blades will last longer since they are cutting a softer material.
One caveat about how often to sharpen blades is that if you hit an object like a rock, stump, or large stick while mowing, you very well may need to sharpen your mower blades again even if you had just started mowing after sharpening them!
Cool Season Reference:
Sharpen after 30 mows of a 1/4 acre -
If you are a homeowner with a 1/4 acre lot. A lot of the US averages 30 mows in a season to maintain a lawn. You should sharpen your mower blades 1 time per year.
Sharpen after 15 mows of a 1/4 acre -
If you are a homeowner with a 1/2 acre lot. You should sharpen your mower blades 2 times per year with an equal number of mows between sharpening.
Sharpen after 60-90 mows of a 1/4 acre -
If you are a lawn mowing company, we assume your mower is mowing 20-30 1/4 acre lots every day. You should be sharpening your mower blades every 2-3 days.
Sharpening Blades When Mowing Warm Season Grasses
Grasses that grow in cool season areas are typically growing in sandy soil. Sand in the soil will greatly reduce the life of a mower blade as the sand will dull the blade quickly.
Just like when mowing cool season grasses, if your blades hit an object other than grass while mowing, you may need to sharpen your blades immediately no matter how long it has been since the last time you sharpened them.
Warm Season Reference:
Sharpen after 5-15 mows of a 1/4 acre -
When mowing warm-season grasses it is much more important to actually use the freshly cut grass blades tips as your reference as to when to sharpen your mower blades again.
The reason being the amount of sand in the soil is going to be the biggest factor as to how often you need to sharpen.
Using a 'sand blade' or 'low-lift blade' can extend the life of the blade because they will not draw as much sand up into the blades/under your deck as you mow.
Learn More About Mower Blades
If you want to know more about lawn mower blades and mower blade sharpening than anyone should ever know, continue reading the blog posts below!
If you need lawn mower blades, we have over 1,000 different mower blades for sale. I bet we have one that will fit your mower! If you need help determining which blade fits your mower, email me.
Related articles:
Everything you need to know about lawn mower blades!
How to sharpen lawn mower blades
Professional Blade Sharpening - Read about the RBG 712 Blade Grinder
Ryan Sciamanna
Ryan is the owner and founder of Lawn Crack, LLC the parent company of iGoPro Lawn Supply. He has worked in almost every capacity within the lawn and landscape industry for small local companies, nationwide companies, and of course, owning his own lawn & landscape business which he sold in 2018 before starting selling lawn and garden products online. Learn more about Ryan by subscribing to the LawnCrack YouTube Channel.
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