Lawnmowers – How to Mow Long Grass Without Damaging Your Mower

Cutting long grass can be challenging, putting additional strain on your garden equipment. If not done correctly, it can lead to uneven lawns, clogged decks, and overheated motors. Here are some expert tips from the team at LawnMaster® for mowing long grass efficiently:

1. Choose the Right Lawnmower for Long Grass

As a general rule, bigger and more powerful lawnmowers, like the LawnMaster 48V 41cm Cordless Lawnmower, are better suited to mowing longer, thicker grass.

Some LawnMaster® mowers, like the LawnMaster 1800W 40cm Electric Lawnmower, include T-Drive™ technology which automatically adjusts the blade speed to cope with the heavy demands of longer grass.

If your current lawnmower has a small deck, a low voltage battery, is old, or is already showing signs of significant wear and tear, consider upgrading it prior to cutting long grass.

Pro Tip for Cordless Mowers: You may notice that the battery power reduces quicker when mowing longer grass due to increased resistance. This is completely normal. Always ensure you fully charge the battery prior to use and consider purchasing a spare battery for larger lawns.

2. Sharpen the Lawnmower Blade Before Cutting

Lawnmowers rely on a blade rotating at high speed to slice clean through grass. Before tackling an overgrown lawn, ensure that your mower blade is secure, sharp, and damage-free. A sharp blade ensures a clean, healthy cut for your lawn.

If the blade is loose, blunt, or damaged, the mower will struggle to cut through the longer grass, which can tear the grass blades or cause the mower to cut out entirely during operation.

Pro Tip: If the tips of your grass turn brown or look ragged a day after you've mown the lawn, it's a sure sign that you need to sharpen or replace your lawnmower blade.

3. Use a Higher Cut Setting (The 1/3 Lawn Rule)

When mowing longer grass, it is vital to start with your mower's highest cutting height setting. You can then reduce the height in stages on subsequent passes until you reach your desired grass length. To protect your mower and maintain lawn health, we recommend never cutting off more than one-third (or maximum half) of the grass height at a time.

Mowing long grass on too short a setting can lead to an inconsistent cut, poor collection performance, and vastly reduced battery run time. It also puts additional strain on the motor, which may cause it to overheat, stall, or cause drive belt breakage.

Pro Tip: Listen to your mower. If the engine sounds like it's struggling, or you notice a reduction in collection performance or any strange burning smells, stop immediately and raise the cutting height.

4. Use a Grass Trimmer on Overgrown Areas First

Alongside edging and trimming, heavy-duty grass trimmers like the popular LawnMaster 24V Grass Trimmer are great at pre-cutting thick, tall grass.

Simply run the grass trimmer over your lawn, concentrating on areas of particularly thick growth and hard-to-reach places to bring the height down. Then, follow up with your lawnmower. Using a grass trimmer first will leave loose grass on the lawn, but this can easily be picked up or mulched by the mower afterward.

5. Reduce the Width of Your Cutting Pathways

When cutting long grass, consider halving the width of your cutting path by overlapping each pass.

Instead of using the full width of the mower deck, only cut with half of it. This reduces the volume of grass being processed at one time, placing less resistance on the blade, leading to a cleaner cut, and preventing the mower deck from getting clogged.

6. Empty the Grass Collection Bag More Frequently

Grass collection bags fill up incredibly fast when mowing long grass. A full grass box can cause blockages in the collection chute, which impacts the run time of cordless mowers and can cause electric machines to stall or overheat.

Keep checking your collection bag fill level regularly and empty it more often than usual. All LawnMaster® mowers come with either a handy indicator that closes when the grass box is full, or a translucent grass box so you can easily see when it needs emptying.

Pro Tip: You may find it more convenient to use a mulching plug when mowing longer grass (provided it's not too damp). This finely chops the mown grass and returns it to the lawn's surface, acting as a natural fertilizer. Remember to follow the height-reduction rules even when mulching.

FAQ: Common Questions About Mowing Long Grass

Can you mow long grass when it is wet?

It is highly recommended to wait until the grass is dry. Mowing long, wet grass causes it to clump together, which easily clogs the lawnmower deck and collection chute, putting dangerous strain on the motor.

What happens if I cut long grass too short?

Cutting long grass too short all at once (known as "scalping") shocks the grass plants, weakens the roots, and leaves your lawn vulnerable to weeds and disease. It can also cause your lawnmower to overheat or break its drive belt.

For more expert advice, along with offers, sign up to our mailing list using the link in the footer.

Ready to Tackle Long Grass? Explore Our Cordless Lawn Mowers

Now that you know how to mow long grass like a pro, make sure you have the right tool for the job. LawnMaster® cordless lawn mowers are designed to handle even the most overgrown lawns — with powerful motors, long-lasting batteries, and smart features like T-Drive™ technology that automatically adapts to tough conditions.

Whether you're maintaining a small garden or a large lawn, we have a cordless mower to suit your needs.

👉 Shop All Cordless Lawn Mowers →