An uneven lawn is more than just an eyesore—it can leave your yard looking patchy, rough, and unhealthy. Whether you use a walk-behind, self-propelled, riding, or zero-turn mower, uneven cutting is a common but fixable problem. Fortunately, most causes can be diagnosed and solved at home with basic tools and a little know-how. This guide walks you through every reason your lawn mower may not be cutting evenly, with step-by-step solutions, maintenance tips, and answers to common questions.
Quick-Check: Why Is My Mower Cutting Unevenly?
- Dull, bent, or damaged mower blade
- Blade(s) installed upside-down or improperly
- Clogged mower deck or built-up grass
- Uneven tire pressure or worn wheels
- Deck not level side-to-side or front-to-back
- Damaged or worn deck hangers or brackets
- Broken, stretched, or misadjusted lift linkages (riding/zero-turn mowers)
- Scalping due to low deck height or uneven ground
- Operator speed too fast or mowing when grass is wet
1. Inspect and Sharpen (or Replace) the Blade
- Disconnect the spark plug or battery before working under the deck!
- Remove the blade(s) and check for dullness, nicks, bends, or cracks.
- Sharpen the blade edge with a file or grinder, maintaining the factory angle. Replace blades that are bent, cracked, or too worn.
- Ensure the blade is installed correctly—cutting edge facing the correct direction (usually the sail/lift wing faces the deck).
- If you have a multi-blade deck, check each blade individually for sharpness and straightness.
2. Check for a Clogged or Dirty Deck
- Grass buildup under the deck disrupts airflow, causing uneven cuts and poor mulching.
- After each mow (or when you notice uneven cutting), scrape and clean the underside of the deck with a putty knife or deck cleaning tool.
- Consider using a deck spray or applying a light coat of vegetable oil to minimize future buildup.
- Always let the mower cool and disconnect power before cleaning.
3. Inspect Tire Pressure and Wheels
- Uneven tire pressure (on riding/self-propelled mowers) causes the deck to tilt, resulting in a lopsided cut.
- Check all tires with a pressure gauge and inflate to the manufacturer’s recommended PSI—usually printed on the sidewall or in your manual.
- Worn, broken, or mismatched wheels can also cause deck tilt—replace wheels if needed for smooth, even mowing.
- On push mowers, ensure all wheel axles are straight and wheels are securely attached.
4. Level the Mower Deck (Riding & Zero-Turn Mowers)
- Park on a flat, hard surface.
- Measure blade tip height at both sides (with blades parallel to the deck). Heights should be within 1/8 inch of each other side-to-side.
- Adjust deck lift linkages or hangers as needed per your manual—usually by turning nuts or adjustment bolts on each side.
- Front-to-back: Most decks should be 1/8–1/4 inch lower at the front for best cut quality.
- Replace worn, bent, or broken hangers and linkage parts as needed.
5. Inspect Deck Hangers, Lift Linkages, and Mounts
- Worn, stretched, or broken deck hangers let the deck sag and cut unevenly.
- Check all mounting points for cracks, bends, or missing parts—especially if your mower hit a stump or rock.
- Replace any damaged hardware, springs, or bushings per your mower’s parts diagram.
6. Operator Technique and Mowing Conditions
- Mow only when grass is dry—wet grass clumps and can leave ridges or scalped spots.
- Overlap each mowing pass slightly to avoid stripes or missed strips.
- Reduce speed when mowing rough, uneven, or bumpy ground—high speed amplifies deck bounce.
- Avoid sharp turns, which can gouge or leave uncut patches.
- Alternate mowing direction every cut to prevent soil compaction and ruts.
7. Avoid Scalping and Adjust Cutting Height
- Set your deck to the highest level that still gives you a clean cut.
- If your yard has bumps or uneven terrain, lower your mowing speed and raise the deck a notch.
- For lawns with high and low spots, consider filling and leveling with soil over time.
- Check that the blade is not bent downward or damaged from hitting rocks or roots.
8. Multi-Blade Decks: Blade Synchronization & Timing
- On riding or zero-turn mowers with two or more blades, all blades must be properly installed and timed (if overlapping types).
- If blades are out of sync or installed incorrectly, missed strips or “step cutting” will result.
- Consult your owner’s manual for proper multi-blade installation and timing procedures.
Preventive Maintenance for an Even Cut
- Sharpen blades every 20–25 hours of use, or at least twice per season
- Clean the deck and inspect for buildup after every few mows
- Check tire pressure and wheel condition monthly
- Level the deck each season or after any hard impact
- Replace deck hangers, bushings, and worn parts as soon as wear is noticed
- Store mower on a flat, dry surface to prevent deck warping
Frequently Asked Questions (FAQ)
Why is my mower leaving uncut strips or “steps” in the lawn?
This is usually due to dull blades, misaligned or damaged deck, uneven tire pressure, or blades installed upside-down. Work through the steps above to correct the problem.
Why is my riding mower cutting lower on one side?
Deck is likely not level side-to-side, or tire pressure is uneven. Level the deck and inflate all tires to the proper PSI.
Can a bent blade cause uneven cutting?
Yes—a bent or unbalanced blade causes vibration, uneven cut, and can damage the mower deck over time. Replace bent blades immediately.
Does mowing too fast cause uneven cuts?
Absolutely. High speed causes deck bounce, missed grass, and poor mulching. Slow down, especially on bumpy ground.
Should I replace the blade or just sharpen it?
Sharpen the blade if it’s just dull, but replace if it’s bent, chipped, cracked, or worn down more than 1/2 inch from the original size.
Conclusion: Enjoy a Perfectly Even Lawn All Season
Most uneven cutting is caused by simple issues: dull or damaged blades, dirty deck, uneven tires, or a misadjusted deck. With a few easy checks and routine care, your mower will deliver smooth, even results every time you mow. Take a few minutes to follow these steps, and you’ll enjoy a lush, beautiful lawn that’s the envy of the neighborhood!
Ready for a flawless cut? Fix the unevenness and keep your lawn looking its best all year!