There’s nothing more disappointing than finishing a mow only to find clumps of cut grass still littering your yard—or worse, your lawn mower bag is barely full. If your lawn mower is not picking up grass the way it should, don’t worry. This is a common problem with clear solutions. With a few easy checks and tweaks, you can get your mower collecting clippings like new and keep your lawn looking tidy and beautiful.
Quick Picks: Most Common Reasons Your Lawn Mower Isn’t Picking Up Grass
- Dull or Damaged Blades: Blunt blades tear rather than cut, leaving behind messy clippings that are hard to vacuum up.
- Clogged Discharge Chute or Bag: Grass, dirt, or debris block airflow, stopping clippings from entering the bag or box.
- Wet or Overgrown Grass: Wet or tall grass sticks together and resists collection, clogging the deck and chute.
- Bag or Catcher Not Attached Properly: If there are gaps or the bag is loose, grass escapes before it reaches the bag.
- Low Engine Speed or Poor Airflow: Low RPMs mean less suction and weaker airflow to move clippings into the bag.
- Damaged or Missing Deck Seal: Air leaks in the mower deck reduce lift and bagging ability.
- Mulching Plug Left In: If your mower is in mulching mode, it won’t send clippings into the bag.
Buyer’s Guide: What to Check First & Tools You Might Need
- Sharp Replacement Blade: A sharp blade is essential for clean cutting and easy pickup.
- Deck Scraper or Putty Knife: For cleaning out built-up grass under the deck and in the chute.
- Gloves and Safety Glasses: Always use when handling blades or clearing blockages.
- Replacement Bag or Catcher: If yours is ripped, clogged, or misshapen.
- Deck Seal Kit: For sealing gaps that weaken airflow (specific to your mower model).
- Leaf Blower or Hose: For cleaning dust and stubborn debris from hard-to-reach places.
Step-by-Step Guide: How to Fix a Lawn Mower That Won’t Pick Up Grass
1. Sharpen or Replace the Blade
- Disconnect the spark plug wire for safety.
- Remove the blade with a socket wrench. Inspect for dullness, chips, or bends.
- If the blade is blunt or damaged, replace it. Otherwise, sharpen with a file or grinder and rebalance.
- Reinstall securely and reconnect the spark plug.
2. Clean Out the Deck, Chute, and Bag
- Turn the mower off and disconnect the spark plug.
- Flip the mower (air filter up) and scrape out all grass and debris under the deck and inside the chute with a scraper or putty knife.
- Empty the bag completely and shake out any clogged or compacted grass. Wash and let dry if necessary.
- Check for blockages all the way from the blade to the bag entry.
3. Avoid Cutting Wet or Excessively Tall Grass
- Always mow when the grass is dry—wet grass clumps and is much harder for any mower to pick up.
- If the lawn is overgrown, mow at a higher setting first, then mow again at the desired height for the best pickup.
- Never try to bag more than 1/3 of the grass blade in a single pass.
4. Check Bag/Catcher Attachment and Seals
- Make sure the grass bag or catcher is seated tightly and there are no gaps where grass can escape.
- Inspect the deck seal or skirt—replace if it’s cracked, missing, or no longer flexible.
- Some mowers have a rear or side door—ensure it closes snugly around the bag or chute.
5. Increase Engine Speed (RPM)
- Always mow at full throttle for maximum airflow and suction.
- If your engine runs rough or doesn’t reach full speed, do a basic tune-up: clean or replace the air filter, replace the spark plug, and check for any fuel or carburetor issues.
6. Remove the Mulching Plug (If Applicable)
- If your mower has a mulching plug or kit, remove it before bagging. The plug blocks the chute, preventing collection.
- Store the plug in a safe place for later use if you want to switch between mulching and bagging.
7. Inspect for Bent or Damaged Deck Components
- Check the mower deck for dents, bends, or warping—these can disrupt airflow and bagging performance.
- Repair or replace any damaged deck parts as needed.
Comparison Table: Why Lawn Mowers Don’t Pick Up Grass
| Problem | Solution | Difficulty | Parts Needed |
|---|---|---|---|
| Dull or Damaged Blade | Sharpen or replace blade | Easy | Blade, wrench |
| Clogged Deck or Chute | Clean thoroughly | Easy | Scraper, gloves |
| Wet/Overgrown Grass | Mow dry, in stages | Easy | — |
| Poor Bag Attachment | Reseat/replace bag | Easy | Bag, seal kit |
| Low Engine Speed | Tune up engine | Easy | Spark plug, air filter |
| Mulching Plug In Place | Remove plug | Easy | — |
| Bent Deck/Chute | Repair or replace | Medium | Deck parts |
Frequently Asked Questions
Why is my lawn mower leaving grass behind?
This is usually caused by a dull blade, wet grass, or a clogged deck/chute. Always mow with sharp blades and clean the deck regularly for best pickup.
How often should I sharpen my mower blade?
Sharpen at least once per mowing season, or more often if you mow over rocks, sticks, or sandy soil.
Can I mow and bag wet grass?
It’s not recommended—wet grass clumps, sticks, and easily clogs both mower and bag. Always let the grass dry before mowing for the best results.
What do I do if my grass catcher is damaged?
Replace torn or misshapen bags. Small holes can be patched temporarily, but a new catcher works best for efficient pickup and airflow.
Why is my mower bag empty even after mowing?
If the bag is empty, you may have left the mulching plug in, have a loose or poorly attached bag, or the deck/chute is clogged. Double-check all components and remove blockages.
Conclusion
A lawn mower that isn’t picking up grass usually has an easy fix—sharpen the blade, clean the deck, clear the chute, and always mow dry grass at full throttle. Check your bag attachment and seals, remove any mulching plug, and do a seasonal tune-up for the best performance. These quick checks will keep your yard clean and your mower running smoothly all season long!