Maintaining a sharp blade is a crucial step to achieving an aesthetically pleasing lawn. Sharp blades and reels give the lawn a nice, neat, manicured look. Dull mowing blades can rip and tear the leaf blade tissue, resulting in a discolored appearance and an unhealthy-looking lawn. A sharp blade minimizes stress on the turfgrass plant, allowing it to recover more rapidly and grow stronger. This also enhances nutrient uptake, making the plant more resilient against drought and heat.
Ragged and torn leaf blades from dull mowing blades are more susceptible to disease. The open wounds allow disease pathogens to enter the internal part of the plant and disrupt the natural pattern of biological growth. A clean and even cut from the mowing blade minimizes the risk of disease and other environmental stress. Healthy and undamaged leaf tissue can photosynthesize better, which leads to more aggressive and vigorous growth.
What Causes Dull Mower Blades?
What causes blades to become dull? There are several reasons for mowing blades becoming dull after use. First, it is normal for blades to become dull over time and require sharpening or replacing. When blades rotate at high rpm’s, the cutting edge of the blade strikes the leaf tissue and reduces the fine, sharp edge over many mowing sessions and time. Grass leaf tissue contains silica that causes an abrasion and dulls the blade.
-
Tiny objects such as rocks, sticks, small branches, and thick thatch can dull blades by curving the cutting edge of the blade and causing an inconsistent cut. Mowing on certain types of soils, such as sandy, loam, or clay, can contain fine particles that also dull blades over time.
-
Mowing wet grass does take a toll on the sharpness because the grass's moisture content is high and thickens around and inside the leaf tissue, which makes it harder for the blade to cut. The increased moisture in the grass tissue will lead to dullness due to the formation of rust on the blade, which degrades the sharpness of the overall blade.
-
Mower blades are normally made of softer steel so they can be sharpened easily. However, because they are made of softer steel, they will naturally become dull after many hours of use. The quality of the steel may be inconsistent in hardness and may contain soft spots, and the metal will wear and become duller than other spots on the cutting blade edge.
-
Mowing the lawn too short brings the cutting blade closer to the ground, which increases the likelihood of cutting more debris and soil, and dulling the blades more rapidly. Cutting through thick grass and thatch requires the blade to work harder and demand more power from the mower's engine.
Dull blades cause the lawn to turn white, and the lawn will appear unhealthy. Grass that suffers from torn and ripped blades can’t fully recover and continually struggles to survive if dull blades and scalping continue. Dull blades can also cause uneven cuts, leave differences in the height of the cut, and visually make the lawn appear “bumpy.” Dull blades cause the mower’s engine to work harder and can slow the rotation speed and the recommended angle to maintain a balanced cut.
A dull blade doesn’t cut the grass cleanly and gives a jagged and frayed appearance. The torn grass blades act as an open wound, making the lawn more susceptible to diseases such as brown patches, dollar spots, and rust. Tearing the grass hinders its ability to recover fully and grow stronger, deeper roots. The damage to the plant's leaf tissue and root system can reduce the amount of water and nutrients that can be absorbed, making the plant more susceptible to environmental stresses. Dull blades can lead to scalping, with the mowing blade tearing the leaf tissue away from the plant's crown.
Mowers themselves are affected by dull blades. Unnecessary strain occurs on the engine and other mechanical components of the mowing system, causing premature wear and shortening the engine's life. When the engine is under increased strain, it burns more fuel, increasing operating costs. In extreme cases, the additional strain can cause the engine to overheat and become damaged. Additionally, oil and lubricants can become degraded and cause more damage to all parts of the mower. Slower mowing and increased effort result from mowers that use dull blades.
Why is a Sharp Lawn Mower Blade Important?
Sharpening mower blades is necessary to ensure a healthy lawn and proper mower operation. Removing mower blades from the mowing deck can be challenging if not performed in a while. Following a routine schedule and taking the time to remove blades and sharpen or replace them makes the removal easier. Before completely removing the blade(s), mark the face of the blade so that reinstallation is adequately performed. Once the blades have been removed, clean the blades with a putty knife or other scraping device to remove old grass clippings, mud, or other stubborn debris. A wire brush will thoroughly clean the blade, which is essential when inspecting and sharpening.
Once cleaned, inspect the blade for smoothness on the cutting edge and cracks. Small indentations can be filed to sharpness, but blades with cracks should be replaced due to safety risks. Ensure the blade lift (portion of the blade bent upward) is not worn or cracked. Check the blade for thinness, as metal can wear and reduce thickness after consecutive sharpenings. If the blade's width has been reduced to 50% or more, the blade would need to be replaced.
How to Sharpen or Replace Mower Blades
The first step in sharpening the blade is to secure it in a vice or work table. Once this has been done, it is time to choose your tool to sharpen the metal: either a hand file, a drill-powered blade sharpener, or an angle grinder.
-
Hand File: Use a mill file and work along the cutting edge at a 30-degree angle. Operate the file in one direction, making smooth and even strokes. Lift the file after each stroke and repeat the process across the front cutting edge of the blade.
-
Drill-Powered Blade Sharpener: Attach a sharpening stone kit to a drill. Use the grinding stone over the blade's edge with the flat guide against the back of the blade to maintain the correct angle. Move the grinding stone back and forth along the edge with medium pressure.
-
Angle Grinder: Use an angle grinder with a flap disc. Align the grinder with the cutting edge and slowly move it back and forth.
The goal is to create a sharp edge, not a razor-sharp edge, because a too-thin blade will chip and wear faster. When using power tools, be cautious of overheating, as this can weaken metal. Dipping the blade in water during the sharpening routine will help keep the metal cool and stronger. The blade is to be balanced after the desired sharpness has been achieved. Once the blade has been balanced, reinstall the blade with the face marking downward.
Sharpen the blade regularly after roughly twenty-five hours of operating time. Clean the blades after each use and check for damage to the blades regularly. By following these steps and procedures, you can maintain a sharp blade, which is much healthier for the lawn.
Choose the Right Types of Mower Blades
Knowing the different types of mowing blades that match your lawn situation is essential.
1. Standard Blades (2-in-1 or Medium-Lift)
-
These are the standard blades that come with new mowers. The metal is curved to create enough air flow to hold the grass upright while cutting and discharge clippings.
-
Regular mowing of well-maintained lawns is desired, with or without discharging or bagging clippings.
-
Not ideal for mowing thick or tall grasses.
2. High-Lift Blades (Bagging Blades)
-
Has an increased curve in the blade to create more airflow
-
Creates a suction action on the grass
-
Excellent for bagging clippings
-
High lift prevents clogging when bagging or discharging
3. Low-Lift Blades
-
Blade has less curvature and creates less air flow
-
Best for dry conditions, sandy soil, or mowing at lower heights
-
Not suitable for bagging clippings
4. Mulching Blades (3-in-1 Blades)
-
Features a curved surface and many cutting teeth on the blade
-
Designed to cut the grass and then chop the leaf blades into tiny particles
-
Best for recycling clippings and reintroducing nutrients back into the growing environment
-
Excellent for lawns that are mowed more than two times weekly
-
Struggles with tall or wet grass
-
Not ideal for bagging clippings
5. Gator Blades (Shredding Blades)
-
A type of “mulching” blade with serrated edges and notches on the edge of the cutting blade
-
Increased mulching power grinds the leaf clippings finer
-
Suitable for mulching leaves in the fall season
-
Excellent for bagging clippings
-
Requires more frequent sharpening due to the serrated edges
How to Choose the Right Blade for Your Lawn
First, decide if bagging or mulching is desired. Is your grass thick-bladed or thin-bladed? What is the mower type? Will it work on every lawn mower? What is the desired outcome? There are many benefits to recycling grass clippings that will save on applied fertilizers, as the nutrients will return into the soil from the decomposing clippings. Bagging has advantages but can create the need for disposal and storage in approved places. Not every mower is the same, and not all types of blades will work properly on all mowers. Mowing within the recommended ranges of height is of the utmost importance, regardless of whether the blades are sharp or not.
Sharp Mower Blades for Grass
Maintaining a sharp blade is one of the most crucial steps. Sharp blades and reels give the lawn a nice, neat, manicured look. A sharp blade minimizes stress on the turfgrass plant. Dull blades cause the lawn to turn white or light tan haze across the surface and cause an unattractive appearance. The torn grass blades act as an open wound, which makes the lawn more susceptible to diseases. Sharpening mower blades is a necessity to ensure a healthy lawn and proper mower operation.
The goal is to create a sharp edge, without being razor-sharp. Be cautious of overheating if using electrical or battery-operated tools. Sharpen the blade(s) every twenty-five hours of mowing time and clean the blades after each use of cutting grass. Knowing the different types of mowing blades that match your lawn situation is essential. There are as many as five different types of mowing blades for the home lawn. The desired outcome and the type of lawn will determine what type of blade is best for your lawn care situation.
