A lawn that looked even before you start mowing can look uneven after you finish. You might see stripes, tall strips, short patches, ragged tips, or areas that look scalped. These signs do not necessarily mean one problem. The mower, method of cutting, soil, drainage and grass growth are all factors that can affect the final result. A careful check can help you find the cause before changing parts or spending money on repairs. First, look at the pattern left by the mower. Then look at the machine and the lawn.
There are a lot of moving parts in the mower that help keep the blade at the right height and speed. A loose belt, a damaged spindle or a bent blade, a wear to a pulley can alter the performance of the cutting system. If you have to replace a lawn mower pulley, get one that fits the model of mower and the deck system. UDC Parts carries mower pulleys and other replacement parts for many common mower applications. What is important is to check the part number and dimensions before installation. A proper part can fix proper blade movement, but it can't fix an uneven lawn surface or poor mowing technique.
Why Does My Lawn Look Uneven After Cutting?
Usually you don’t notice an uneven cut until you’ve mowed the same area twice. One patch may appear smooth, another will have visible strips of taller grass. You may also notice some grass tips look clean, while others look torn or brown. The pattern gives you a tip as to where to begin looking. A mower problem is often repetitive in a regular pattern. A lawn problem, however, is bumps, dips, shade or thin growth. By good daylight inspect the finished lawn, when changes of level are more easily seen.
The mower should cut to a consistent height over the full width of the deck. If the deck is inclined then one side of the blade could be lower than the other. If the tire pressure is low, a similar problem may occur. The mower body is no longer at the intended height. Grass that is packed under the deck can also restrict airflow and affect the way clippings exit the cutting chamber. A dull blade will tear the tips, rather than cutting them cleanly. When several problems occur at the same time the final lawn appearance can be much worse than the original fault indicated.
How To Tell If The Problem Is The Mower Or The Grass
Check the pattern before you touch the mower. If the same strip is taller each time you mow, check the blade, deck, spindle, belt and pulley system. If the roughness occurs only where the ground is sloping up or down, the soil may be mostly to blame. Compare the cut on a smooth part of the yard to the cut on a rough part. Or walk across the lawn and feel for bumps or mushy spots that the mower follows. This simple test serves to distinguish between machine faults and ground conditions.
Common mower problems that result in an uneven cut
The mower parts should cooperate to keep the blade level and spinning at the right speed. A dull, bent, cracked or off-balance blade may give different cutting results over the deck. Vibration from a damaged blade can also be a sign of a more serious mechanical problem. Tire pressure is important because the deck height depends on the mower being at the correct position. If one tire has a lower pressure than the others, one side of the deck may be sitting lower. Even with the correct tires, an out of level deck can produce a similar pattern.
Grass build-up under the deck is another frequent cause of poor cutting. Wet grass clippings can mat into a thick layer that restricts airflow and changes how the grass moves through the deck. Clean the underside only when the mower is off, cool and secured in accordance with the owner’s manual. Look for any bends in the blade and check the mounting area for loose parts. If the mower vibrates, stop using it until you can find the reason. Damaged or bent spindle or pulley, worn spindle bearings, or a bent spindle can affect blade rotation and require repair rather than just a cleaning.
How Mowing Height & Method Impact the Lawn
If you mow incorrectly, even a healthy mower can leave your lawn looking uneven. If you cut too low you’ll show the high spots and make the low spots look darker or longer by comparison. Wet grass also makes it hard for a mower, because the clippings stick together and the blade has more resistance. If you cut too fast, the cutting system won’t process the grass evenly. Going over the same path can leave distinct wheel marks and alter the way the grass stands. Good mowing means the right cutting height, dry conditions, steady speed and consistent overlap.
Cutting height, mowing speed and wet grass
Instead of mowing a lot of grass at once, adjust the cutting height to the type of grass and season. If the lawn has grown tall, raise the deck and make a second pass later, rather than forcing the mower to cut too much grass. Tall strands can be left as wet grass bends beneath the deck and slides past the blade. It can also clump up and adhere to the surface of the deck. Keep a steady pace to allow the blade to keep up with the amount of grass coming into the deck The mower can only produce an even cut if the cutting system and the surface beneath it work together.
Problems in Grass and Soil That Cause an Uneven Lawn
Sometimes it’s not the mower that’s the issue. Any lawn that has bumps, low spots, exposed roots, compacted soil or poor drainage can look uneven after each cut. The mower follows the ground with the blade rising over high spots and dropping down into low spots. That makes the space between the blade and the grass. Raised sections can become too short, and grass in low spots can be tall. And even when the machine is level, well maintained, the end result can look like a mower fault.
Thin grass and bare patches can make a lawn look uneven too. Grass may not grow well in soil that is compacted, collects water, has damaged roots, or is low in sunlight. Weak areas may leave more soil uncovered after mowing than healthy areas. Heavy traffic can compact the soil preventing root growth and water movement. This develops into a mottled surface over time that cannot be corrected with mowing alone. Check on the lawn before mowing to see if the uneven spots are already there, without new cutting marks.
How to Repair an Uneven Lawn After Mowing
Fix the problem in a certain order so you don’t change good parts without checking simple causes. Begin with the mower, as a small mechanical problem can affect the entire pattern of cut. Then check the lawn surface and mowing conditions: A practical sequence of steps is as follows:
Check the blade for dull edge, bends, cracks or other damage and replace if it cannot be safely restored.
Check the pressure of the tire against the specs from the mower manufacturer and correct any difference from side to side.
Remove any grass that has grown under the deck, and inspect the deck for any signs of damage or loose parts.
Check deck level on a level surface and adjust as per the owner’s manual.
Set the cutting height to a suitable height and don’t cut the grass too short at one go.
Walk the lawn and mark bumps, dips, thin spots and drainage problems.
Mow dry grass at a slow, steady pace and change directions between mowing sessions.
Once these checks have been made, cut a small test area before cutting the whole lawn. Compare this result with the earlier pattern, and see if the same strips remain. If the cut improves the problem was probably related to the mower or mowing method. If those same areas are uneven, focus on soil, drainage, grass density and surface grade. If the ground is the problem, don't keep playing with the mower. Clear diagnosis saves time and avoids unnecessary parts replacement.
Tips to Avoid Uneven Mowing in the Future
Prevention begins with routine checks rather than waiting for an obvious cutting problem. Keep the blade in good shape during the season and check it after hitting stones, roots or other hard objects. If the mower manual specifies a tire pressure range, be sure to check the tire pressure before each mowing session. Keep deck clean to prevent grass build-up around the blade area. Choose a suitable cutting height for the grass and do not take off more than a reasonable percentage of the leaf height at a time. Mow when the grass is dry enough to stand and pass through the deck.
These simple habits can also help to keep the lawn surface and the mower working together:
Check the blade and deck before the mowing season and after hard impacts.
Check tire pressure, and both sides for discrepancies and maintain pressure.
Remove grass build-up from deck after mowing as necessary.
Alternate the mowing direction between sessions to avoid repeated wheel patterns.
Fix and patch persistent bumps, dips and drainage problems in your lawn.
Slow down when the grass is tall, thick or uneven to allow the blade to maintain a steady cut.
When to Repair or Replace Mower Components
Some ragged cuts are proof of maintenance being done, some are proof that a part needs to be repaired or replaced. You can often hone your blade if it is straight and not damaged. A bent or cracked blade should be replaced as continued use can result in vibration and unsafe operation. If the deck is vibrating or the blade is not turning, you can also inspect the pulley or spindle. An old pulley or spindle can affect how the blade moves. An online source for mower parts can be handy, but always verify your mower model and part number first. Never install a part merely because it looks the same, similar looking parts may have different dimensions or mounting requirements.
Don’t ignore repeated vibration, strange noise or a loose-looking blade. The signs could be indicative of a mechanical wear that will not be improved by mowing technique alone. Refer to the mower manual for blade removal, spindle inspection and deck adjustment. If you can not detect the fault yourself, a professional lawnmower repair service can inspect the cutting system.
Your lawn is uneven after mowing. That doesn’t always mean you need a major repair on your mower. Common causes include dull or damaged blades, uneven tire pressure, a level deck, grass buildup, poor mowing technique, and rough lawn surfaces. Try simple checks first, using the pattern of the grass for a clue. “Be sure that the mower is the problem before you correct it. If the ground is uneven, bumps, low spots, drainage and thin growth should be addressed as part of the lawn care plan. A well-tuned mower, correct mowing height, dry grass and a consistent technique will help you to keep your lawn more even from mowing session to mowing session.
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