Why you Need to Keep your Mower Blade Sharp!

Is this one of the last or first things you think about before mowing your lawn. Grab your beer, check the oil, put some gas in and off you go! Well by doing that you maybe off to a head start but you’re definitely putting your lawn in the pits. A sharp balanced mower blade is essential for a high-quality cut. The aftereffect of a dull cut impacts the turf for weeks.

So, what happens when mowing with a dull blade?

The plant can’t heal, it uses more water, it becomes susceptible to disease, root development is stunted, and top growth is slowed.

Instead of creating a crisp cut from a sharp-edged blade, a dull blade leaves a ragged and frayed edge that doesn’t close. The grass blade is pulled apart with force instead of sliced with ease. This leaves a ragged frayed edge that the grass plant struggles to heal. Why?

Because plants produce small amounts of hydrogen peroxide in order to seal wounds. Remember when you were a wee one and your parent would put hydrogen peroxide on a cut to close it hygienically. The grass plant does the same thing……Amazing Right!!! Well, if there is a ragged edge, the plant doesn’t have enough stored in order to close the wound. Compound this with the grass trying to heal and put energy into damaged cells and the result is a weak plant that has wounds that are open to infection. Wounds that are continually weeping creates one criterion to start the disease triangle. Do this in the height of summer and you could have a battle on your hands that was created accidently. A clean cut ensures a solid seal where water and nutrients are not lost, cells can operate effectively because they will be provided with essential development nutrients and carbohydrates. Regrowth is focuses on cell division and not repair allowing the plant to maintain optimum photosynthesis.

But why is root growth stunted? That doesn’t make sense.

Grasses carry out photosynthesis in order to produce sugars. These sugars are then used to develop new parts of the plant like, membranes, tissues, cells, cuticles and everything else. If part of the grass is damaged, cut, bruised or broken, the plant will concentrate its’ effort to that location. When the location is not sealed it leads to carbohydrate loss until its eventual seal which could take days. During that time all the necessary components for root development and function are being redirected. Consequently, root function is being inhibited leading to a reduction in water and nutrient uptake. Ultimately, a compounded problem has just occurred. The plant is losing water and nutrients from open wounds whilst the plant is struggling to supply itself with more water and nutrients. If this happens during a hot dry weather pattern it could lead to major turf health loss; will impact its root development for weeks until it can generate enough sugars again to supply above and belowground. As a result, you will need to apply more maintenance to your lawn because all of a sudden, your lawn is requiring more water and is rapidly using more fertilizer. Therefore, costing more money!

In summary, mower blades should be kept sharp and reground every 20-25 hours of use. So, in the northern states if you mow 1 hour per week you should get your blades sharpened before first mow of season and in the middle of the summer.

Additional Thoughts to Consider

Do not use a blade that has more than 25% of the face removed. This leads to inadequate operation and quality of cut.

Make sure to use the right type of blade (no-sail to gator blade) and make sure your machine has the horsepower to spin the chosen blade at the right speed. Low RPMs result in a ripped grass blade again.

Make sure your mowing deck has a slight taper front to back. 1/8th – 1/4″. This is called mowing attitude and incorrect attitude puts a strain on the engine as it requires more horsepower.

Keep the underdeck clean and free of debris, a dirty deck reduces air flow, slows the rotation of mowing blades. Same result; ripped grass.

Never grind the bottom edge of a blade, always just the face. This increases horsepower usage and reduces quality of cut.

Always balance the blade after sharpening. Too much weight on one end will cause shaft and engine problems eventually whilst producing an uneven cut.