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How to use a mulching mower

Updated: October 2026

The lawn looks fluffy with clumps, and the mower from Saturday is getting the blame. How to use a mulching mower starts with the grass. Dry, short growth can be recut and left. Long or wet growth should be collected, or cut high, until the sward is ready again. The machines in the [mulching lawn mower comparison](/hub/lawn-and-garden-equipment/mulching-lawn-mower) illustrate a plug, a wedge or a hover. The Products Compared editorial team followed Royal Horticultural Society guidance and the review themes in the 19 October 2026 amazon.co.uk files. There is no fertiliser rate here. A qualifying purchase can earn a commission at no extra cost to you.

The lawn looks fluffy with clumps, and the mower from Saturday is getting the blame. How to use a mulching mower starts with the grass. Dry, short growth can be recut and left.

Our top picks

Einhell Einhell GE-CM 43 Li M

Best overall

Einhell Einhell GE-CM 43 Li M
7.9/10about £239.94
View offer
LawnMaster LawnMaster MEH1633M-01

Best value

LawnMaster LawnMaster MEH1633M-01
7.0/10about £69.00
View offer
Murray Murray LE380

Rank 3

Murray Murray LE380
8.5/10about £152.65
View offer
On this page
  1. 1.Mulch only when the lawn is ready
  2. 2.Height and how much you take off
  3. 3.Plug, box, or hover
  4. 4.When to collect instead
  5. 5.Clearing the deck

Mulch only when the lawn is ready

Walk the grass before you start the motor. The RHS says never mow wet or frosty grass. Wet clippings clog a mulching deck, and wet soil compacts under the wheels or under a hover's repeated passes. If the lawn is dry and you are taking a modest bite, mulch mode is the right job. If your shoes are wet by the far edge, collect this cut or wait. A battery does not make light rain safe, and a hover does not make a soaked lawn a mulching day.

Height and how much you take off

The RHS how-to uses the one-third rule: do not take off more than about a third of the leaf in one pass. If the grass is 9 cm, a first pass that aims at 3 cm breaks that rule. Leave it longer, then come back on a later dry day. For a conventional lawn the same guidance puts spring and autumn around 4 cm and summer around 2.5 cm. Use the closest step the mower has. If a holiday has left the sward at twice the usual height, the one-third rule means two or three visits, with the box on for the first of them.
Einhell Einhell GE-CM 43 Li M

Testsieger

Einhell Einhell GE-CM 43 Li M
7.9/10about £239.94
View offer

Plug, box, or hover

On a 2-in-1, mulch mode means the plug or wedge is seated and the chute into the box is closed. Murray reviews often call that attachment awkward, so try it in the shed before the grass is long. If you cannot see how the plug fits, collect until you can. A hover such as the LawnMaster has no box to remove and no plug to lose. The RHS still wants narrower passes when a hover meets long grass. If the clippings land in rows, you are in drop mode or the grass was too long for the plug.

When to collect instead

Collect this week, and mulch the next dry one, when one pass would remove more than about a third of the leaf, when the lawn is wet or was frosty, when leaves are thick enough to mat, or when the turf looks diseased and you would rather lift the clippings than spread them. The RHS garden-waste guidance allows short, dry clippings, including pieces under about 1 cm, to stay on the lawn. It does not ask you to mulch a hayfield.

Clearing the deck

Isolate the power before your hands go under the deck. Electrical Safety First says unplug a mains mower. Take the battery pack out of a cordless one. Use a stick or the scraper the maker supplied. If the cable is nicked, or the pack is swollen, stop. A new outdoor socket or a missing RCD is an electrician's job. A steep bank beside water is someone else's work: a hover is not self-propelled.

Common questions

How short should the clippings be before I leave them?
The RHS garden-waste page treats short, dry clippings, under about 1 cm, as material you can leave even from a normal mower. A mulching plug is trying to produce that kind of fragment, scattered into the sward. If you can still see rows or plates of grass the morning after, the bite was too deep or the grass was damp. Collect or rake those clumps off, then mulch again when the lawn is shorter and dry.
What height do I start on in spring?
Start high. The one-third rule still applies, so a lawn at 8 or 9 cm does not drop to a summer height in one Saturday. RHS guidance for a conventional lawn is about 4 cm in spring and autumn and about 2.5 cm in summer. Use the closest step your mower has. The LawnMaster's 12 mm bottom step can scalp bumps, so leave it for a later, flatter pass if you use it at all.
What do I do if I see clumps?
Stop treating the clumps as a mulch. Rake or collect them so they do not smother the grass. Check that the plug is seated, then raise the height and wait for a drier day. The next modest pass, once the lawn has dried, is the one that goes back to the plug.
Can I mulch leaves?
A light scatter of dry leaves can go through with the grass. A thick fall that mats is a collecting or raking job, because the deck will throw plates of leaf. If the leaves are wet, wait until they are dry or pick them up. Diseased foliage is the same decision as diseased grass: lift it rather than spread it across the lawn with the mulch plug.
How do I clear a packed deck safely?
Switch off, unplug the corded mower or remove the battery, and wait until the blade has stopped. Scrape with a tool, and follow the manual for which way to tip the deck. If the cable is damaged, or you cannot free the chute without force, stop. A repaired lead or a new outdoor socket is an electrician's job.
When should I stop and call someone?
Call an electrician if you need a new outdoor socket, or if the garden circuit has no RCD and you are about to run a mains lead across the lawn. Stop if the cable, the deck or the battery pack is damaged. Do not take a pedestrian mower onto a steep bank beside water. A hover has no self-propelled control. The cut can wait.

Related pages

Mulching lawn mower buying guide

Mulching lawn mower for small lawns

Corded or cordless

Mulching lawn mower

Best mulching lawn mower: who should pick and skip

Sources

Public UK sources from the research digest. Amazon.co.uk prices and star lines are from the files dated 19 October 2026. Last checked 23 October 2026.

  1. RHS, lawn mowing (retrieved 19 October 2026)
  2. RHS, garden waste (retrieved 19 October 2026)
  3. Noise Emission Regulations 2001, Schedule 3 (retrieved 19 October 2026)
  4. GOV.UK, outdoor noise (retrieved 19 October 2026)
  5. Electrical Safety First, lawnmowers (retrieved 19 October 2026)
  6. GOV.UK, UKCA and CE marking (retrieved 19 October 2026)
  7. GOV.UK, battery recycling (retrieved 19 October 2026)
  8. Which?, lawn mower buying notes (retrieved 19 October 2026)