How to cut long grass without stalling the UK mower
Updated: October 2026
When you return from a long holiday, or face the first cut of the year, the quickest-looking solution is often the one that causes trouble: setting the mower low and forcing one pass. Learning how to cut long grass means checking the area first, taking the height down in stages, and stopping when the machine says the job is beyond it. If you still need a suitable machine, start with the [tall grass mower comparison](/hub/lawn-and-garden-equipment/tall-grass-mower). If you already own a rotary or hover, the sequence below is for a recovery cut, not an ordinary weekly mow.
When you return from a long holiday, or face the first cut of the year, the quickest-looking solution is often the one that causes trouble: setting the mower low and forcing one pass.
When you return from a long holiday, or face the first cut of the year, the quickest-looking solution is often the one that causes trouble: setting the mower low and forcing one pass. Learning how to cut long grass means checking the area first, taking the height down in stages, and stopping when the machine says the job is beyond it. If you still need a suitable machine, start with the tall grass mower comparison. If you already own a rotary or hover, the sequence below is for a recovery cut, not an ordinary weekly mow.
Our top picks
| Badge | Product | Cut height | Width | Collection | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  swift swift EB122C | 30–50 mm | 22 cm | Mulch, no box | 8.6 | about £134.99 | View offer |
 Einhell Einhell GC-EM 1600/37 | 20–60 mm | 37 cm | 38 L box | 8.7 | about £114.99 | View offer | |
| Preis-Tipp |  BLACK+DECKER BLACK+DECKER BEMWH551-GB | 20–40 mm | 30 cm | No box listed | 8.0 | about £49.99 | View offer |
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Look before you start the motor
Walk the area with the machine unplugged or the battery out. Remove stones, wire, toys and branches. Long grass hides bumps and holes. Keep a cable behind your direction of travel.
Hedgehogs may shelter in long grass, especially under hedges. Check dense patches by hand with gloves. Active wild-bird nests are legally protected in Great Britain. If you find one, leave a generous undisturbed area. Northern Ireland has its own legislation. Across the UK, do not cut an occupied nest.
Wait until grass and soil are reasonably dry. Wet clippings stick under the deck and add load. A Flymo owner in this set reports trouble in long wet grass, and the same problem affects every mower. Measure the dense body of the grass against the highest setting. The mower for long grass buying guide explains why 31–40 mm and 60–70 mm are different starting points.
Take the height down in stages
Set the highest position for the first pass. RHS and STIHL use the one-third rule: remove no more than about one-third of the leaf at one time. A lawn that finishes at 25 mm cannot drop from 100 mm in one afternoon. Walk slowly, overlap, and on a hover use about half the swath where growth is heavy. Stop if motor speed stays down.
A 31 mm Flymo or a 40 mm BLACK+DECKER hover may be unable to make a safe first pass through genuinely long grass. Do not prop the deck up or remove guards. Reduce the growth with a strimmer, brushcutter or scythe, rake, then mow high. Strimmer or mower for long grass sets which tool goes first. Grass around six inches is a UK warning point, not an engineering limit. Brambles and woody stems are a clearing job.
Keep the deck and collection path clear
Long clippings fill a box much faster than a weekly cut. Empty it before it is rammed full, even if the indicator has not moved. Einhell owners report that the flap does not always show a full box. A 15 L Flymo collector needs frequent stops. Falling collection, a trail of clippings and a blocked chute mean you stop.
Unplug the mower or remove the battery, and wait until the blade has stopped, before you clear the chute. Do not mulch a heavy recovery pass. A mulching deck recuts small dry clippings. It cannot make a hay-like volume disappear. One owner says the Hyundai HYM3800E mulch plug blocks the collector. Collect or rake the long material, and change direction later so flattened stems lift.
Make the later cuts, and recognise the stop signs
Leave the lawn a few days before you lower the deck. Lawnsmith suggests roughly two or three days. Take the next sensible height rather than a summer finish. Yellow lower stems were shaded, so give them time. RHS puts an ordinary summer lawn around 13–25 mm. STIHL describes many recreational lawns at roughly 3–5 cm. Neither figure is the first recovery pass.
Stop if the motor cuts out, smokes, smells hot, or keeps losing speed after you narrow the swath. Reviews here include the Hyundai HYM3800E overloading and a FORTE motor smoking. Disconnect it and follow the manual. Do not force a Flymo blade bolt that will not move when you fit height spacers. A managed meadow should not follow this lawn schedule. Read cutting a wildflower meadow before you turn every long patch into short turf.
Common questions
Should I cut long grass in one go?
No. Start on the highest setting and remove no more than about one-third of the leaf. Return after a few days for a lower pass if it recovers. One very low cut risks clogging, overload, scalping and a yellow lawn.
Do I need to strim before mowing?
Strim first when the dense grass is too high to enter the deck, or when your mower's maximum setting is only 31–40 mm. Check carefully for wildlife, reduce the growth with the appropriate tool, then rake it. The mower can make the later level cut once the remaining height is manageable.
Can I mow long grass when it is wet?
Wait if you can. Wet long grass clumps under the deck, blocks collection and makes the motor work harder, while sodden soil is easily rutted. If the weather leaves no perfect window, postpone rather than assuming a higher-powered mower removes the electrical, traction and clogging risks.
Why has the grass box stopped collecting?
The box, chute or deck may be packed with damp clippings. Disconnect the power and wait for the blade to stop before you look. Empty it early on a long-grass cut, and do not rely only on the fill indicator.
What should I do if the mower smells hot?
Stop, disconnect it and let it cool. Check the manual for permitted blockage inspection and maintenance. Do not restart repeatedly to see whether the smell disappears. Smoke, persistent cut-outs or a hot electrical smell can indicate overload or failure and may need a repairer.
How long will yellow grass take to green up?
There is no fixed guarantee. Recovery depends on weather, soil and how much leaf was removed. Yellow lower stems were shaded while the grass was long and may improve as new growth develops. Give the lawn several days, water only if conditions require it, and avoid another severe cut.
Related pages
Sources
Sources checked for this comparison; last retrieved on 17 October 2026.
- RHS, wildflower meadow maintenance (retrieved 17 October 2026)
- RHS, lawn mowing (retrieved 17 October 2026)
- RSPB, Wildlife and Countryside Act (retrieved 17 October 2026)
- Control of Noise at Work Regulations 2005 (retrieved 17 October 2026)
- Control of Vibration at Work Regulations 2005 (retrieved 17 October 2026)
- Which?, how to buy a lawn mower (retrieved 17 October 2026)
- RHS, hedgehog-friendly gardening (retrieved 17 October 2026)
- Homebuilding, how to cut long grass (retrieved 17 October 2026)