No matter how warm the sunlight, moist the air and nutrient filled the soil is the health of your grass may come down to a razors edge. Always start the season with sharp blade edge and a clean deck. A sharp, clean lawnmower blade produces a clean cut through grass plants. A quality cut reduces water loss and fatigue on the grass plant. After the initial cut through the grass plant a sharp blade greatly reduces the clippings into fine mulch. Small clippings return to the soil surface and feed your lawn.
New vs. Sharp vs. Dull
Let’s explore what a dull blade does to your lawn and the benefits of new and sharpened blades.
A dull blade
A dull blade leaves grass plants ripped or torn. When grass is torn or loses excessive water, the tips will turn yellow or white. A lawn full of dry, yellow grass is a clear indication that your lawnmower blade is damaging your lawn. A poor blade edge also leaves clumps of grass across your lawn. These clumps block the grass plants from vital sunlight and air. Excess grass clippings may also produce thatch between the soil and air. This effectively chokes your lawn.
Start the season with a sharp or new blade. Keep track of the hours or number of mows you perform. Typically, blades dull after 8-12 hours of use. Visually inspection is not ideal but any nicks and imperfections along the cutting edge demonstrate a dull blade.
A brand new blade
Genuine factory blades (or Original Equipment Manufacturer) feature the optimal cutting edge both for quality of cut, efficiency and longevity. Lawnmower blades are designed to make a clean cut while remaining effective over a long period of time. For this reason, new blades are never razor sharp or even as sharp as a knife edge. The cutting surface is durable across multiple hours and withstands unseen hazards like small twigs, leaves and in some cases litter. Generally, a new blade may remain productive for 8-12 hours of use. For some homeowners this may be a complete mowing season while others will need to sharpen throughout the season.
A Sharpened Blade
Freshly sharpened blades will perform as well or better than a new blade. The cutting edge is so sharp that we coat blades in wax to protect our staff and homeowners when handling sharpened blades. This razor edge cuts through your lawn extremely well.
There are key differences between new and sharpened blades: Sharpened blades dull quickly. The razor edge wears quicker than factory blades. Sharpening a blade exposes the metal to oxidation. Blades should be carefully balanced during sharpening to prevent damage to lawnmower engines and spindles. Some blades should not be sharpened because of wear or damage. Any nicks, chips, warping or rounded edges should be considered before sharpening a blade.
The first image is a blade with excessive chips and nicks. This blade has not been sharpened frequently and should be replaced.
The middle blade is bent. Striking anything in your yard often results in bent blades. Any alteration in the blade may damaged your engine or deck spindles.
The far image shows excessive wear. Eventually a blade must be replaced even if the blade is sharpened regularly.
Our Best Advice
I follow the rule of warm season holidays. I sharpen or install a new blade at the start of the season. I sharpen around Memorial Day, Fourth of July and Labor Day. You can also keep track of how long it takes to mow your lawn and create your own schedule based on sharpening every 8-12 hours of use.
Removing your blade is pretty simple. Refer to owners manual for guidance on turning walk mowers onto their side (always disable the spark plug from the ignition coil and be aware that air intake must be facing upward when servicing your mower). Blades typically are secured with a single bolt and washer (Honda uses 2).