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Lawnmower Problems

Why isn't my lawnmower collecting grass properly?

If your lawnmower isn't picking up grass clippings properly, here are six possible reasons and ways to fix them to improve the grass collection performance.

It's essential to understand that, with a few exceptions, grass collection relies on airflow. On most lawnmowers, the rotating blade generates airflow which transports the cuttings into the grass bag.

If airflow isn't being generated properly or the airflow is restricted for some reason, the lawnmower's ability to pick up the grass will be impaired.

6 tips to improve grass collection

Grass collection

Check your grass bag isn't clogged

A lawnmower grass bag is actually a filter, catching the grass cuttings inside whilst allowing air through the holes in the fabric. When the small holes become clogged with old grass, the air flow will be restricted and affect the lawnmower's ability to collect the grass. This is one of the most common causes of poor grass collection.

If the lining of your grass bag is clogged with old grass you should clean it using a jet wash, air line or simply a brush and water. Once clean the air should flow through the grass bag more efficiently and improve the grass collection.

Keep your lawnmower blade in a good condition

On most lawnmowers it's the blade that generates the flow of air. A worn or damaged blade will not generate as much air flow as a new blade, so it may be time to repair or replace your blade.

Please read this safety warning before inspecting your blade.

Don't cut too much grass at once

If your grass is long and you are trying to cut it too short, the volume of grass cuttings may simply be too much for your lawnmower to collect at once.

Our advice is to raise the height of cut on your lawnmower and cut lower more gradually. For the health of your lawn, a widely accepted tip is to never cut more than 1/3rd of your grass height at a time.

Avoid cutting too low

In order for airflow to be generated, air must be able to get into the under side of the cutter deck. If the cut height is set too low, particularly if the ground is covered in thick grass or moss, an insufficient amount of air will be able to get underneath to generate the required airflow to collect properly.

This can be easily solved by raising the cut height, which raises the deck, and allows a greater amount of air to get underneath the deck.

Ensure your cutter deck is clean

The shape of your lawnmower cutter deck is designed to enhance the airflow through to your grass bag. When the underside of the deck is dirty and clogged with old grass, the airflow is disturbed.

Clean the underside of your cutter deck and remove any clogged grass.

Please read this safety warning before inspecting the underside of your cutter deck.

    Avoid cutting in wet conditions

    Wet grass doesn't collect as well as dry cuttings. It's heavier so requires more uplift to be transported into the grass bag, and it's more likely to clump together and stick to your cutter deck or grass bag chute.

    Clumped grass that's stuck in your mower will affect the amount of airflow that can be generated, meaning the grass collection on future cuts of dry grass may be affected too.

    Make sure to keep the underside of your lawnmower clean and clear of any grass clumps, and avoid cutting in wet conditions.

    Still having issues with grass collection?

    If you've tried the each of the suggestions above and are still having issues with grass collection, it's possible there is a wider issue with performance. Speak to your local garden machinery dealer where a trained technician will be able to identify any faults and undertake any repairs if necessary.

    For users in the Yorkshire and Lincolnshire area you can book a service or repair with F G Adamson & Son.

    Safety Warning

    Before tilting your lawnmower to examine the underneath of your cutter deck or blade, please do the following to prevent your lawnmower from starting accidentally:

    • Petrol Lawnmowers - Remove the spark plug cap
    • Electric Lawnmowers - Unplug the power cable
    • Cordless Lawnmowers - Remove the battery

    Always consult your owner’s manual for instructions on the correct way to tip a petrol mower to prevent petrol leaks and other potential damage.

    Posted: 30 June 2022

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