Independent comparisons. We may earn from shop links. More info

Mulching mower vs grass box: which cut this week

Updated: October 2026

You are standing over the lawn with a plug in one hand and a grass box in the other, and the grass was wet at breakfast. This page is mulching mower vs grass box: mulch, collect, or the side-discharge description that often gets sold as mulching. It is not a voltage guide and not a brand ranking. Fitting the plug, step by step, is on [how to mulch mow](/hub/lawn-and-garden-equipment/cordless-mulching-lawn-mower/sub/cordless-mulching-lawn-mower-how-to-mulch). The eleven listings and their GBP prices are on the [cordless mulching lawn mower comparison](/hub/lawn-and-garden-equipment/cordless-mulching-lawn-mower). Peter F. followed the RHS and Warwickshire in October 2026. A qualifying purchase can earn a commission at no extra cost to you.

You are standing over the lawn with a plug in one hand and a grass box in the other, and the grass was wet at breakfast.

Our top picks

Swift Swift EB122C 22 cm

Best overall

Swift Swift EB122C 22 cm
9.0/10about £134.99
View offer
Worx Worx WG737E 37 cm kit

Rank 2

Worx Worx WG737E 37 cm kit
9.0/10about £229.00
View offer
Einhell Einhell GE-CM 18/33 Li kit

Best value

Einhell Einhell GE-CM 18/33 Li kit
8.6/10about £149.95
View offer
On this page
  1. 1.Three ways the clippings leave
  2. 2.When to mulch and when to collect
  3. 3.Machines that can switch, and machines that cannot
  4. 4.What to do this week

Three ways the clippings leave

A mulch plug, or a mulching blade, keeps clippings under the deck so the blade recuts them and they drop into the turf. Warwickshire describes that as a shaped blade and airflow doing a second cut. A grass box stores one cut. Side discharge throws longer pieces out to the side. Treating that spray as mulching is how a lawn gets a thatch on top of the grass. The WG737E, the Bosch kit, the Hyundai, the Ryobi and both Greenworks models state a plug or a 2-in-1 path, and they state a bag. The Swift states a super-mulch blade and does not state a bag. The Einhell bullet says mulching is side discharge and that there is no bag, while a highlight mentions a 30 litre box. Do not treat those lines as one settled spec. The WG779E, the Yard Force and the Litheli do not state mulch. A roller stripes the lawn. It does not recut clippings.

When to mulch and when to collect

Mulch when the grass is dry and you are only taking about a third of the leaf. That figure is Warwickshire’s rule of thumb. In a drought, raise the cut and leave short clippings. Collect when the grass is long, wet, full of leaves, or fungal problems are the reason the clippings should leave. A 2-in-1 deck is a compromise. The Swift avoids that compromise by refusing the bag, so a wet Sunday means you wait.
Swift Swift EB122C 22 cm

Testsieger

Swift Swift EB122C 22 cm
9.0/10about £134.99
View offer

Machines that can switch, and machines that cannot

You can switch, plug in or plug out, on the WG737E, the Bosch kit, the Hyundai, the Ryobi and both Greenworks mowers, because those listings name a mulch path and a box. The WG737E is the top pick when that switch is what you want on a medium lawn: about £229.00, 37 cm, two 4.0 Ah packs, 4.5 from 207 reviews. A short review on a Greenworks 2 Ah pack does not stop the plug working. It does stop you finishing a claimed 250 m² on that pack. You cannot switch on the Swift, because no bag is stated. Do not assume you can switch on the Einhell. You cannot switch for mulch on the WG779E, the Yard Force or the Litheli. Ryobi’s plug can arrive already fitted. The Yard Force roller is for stripes, not a mulch path.

What to do this week

If the grass is dry and you are only taking about a third of the leaf, fit the plug on a listing that names one, and mulch. If the grass is wet, long or leafy, take the plug out and use the box. The mower has to state both paths, or you accept the Swift’s mulch-only limit and wait for a dry day. Do not call side discharge mulching in order to force the Einhell into that sentence. Wet grass that stalls a Ryobi will not become a clean mulch because you prefer not to empty a box. For this Sunday, the weather and the length of the grass outrank the badge on the carton.

Common questions

What is the difference between a mulch plug and side discharge?
A mulch plug blocks the exit so the blade recuts clippings and drops them in the turf. Side discharge throws longer pieces out beside the mower. On the Einhell, the bullet uses mulching for side discharge and also says there is no bag, while a highlight mentions a 30 litre box. Those are not one specification.
When is the grass box the better choice?
Use the box when the grass is long, wet or full of leaves, or when fungal problems mean the clippings should leave. The RHS notes collecting as a help where fungal trouble is a concern. A dry, short cut of about a third of the leaf is the week for the plug, on a mower that states one.
Can one mower do both?
Yes, if the listing states a plug and a bag: the WG737E, the Bosch kit, the Hyundai, the Ryobi and both Greenworks models. You still change parts between cuts. Warwickshire treats that 2-in-1 arrangement as a compromise. The Swift does not offer the bag in this capture.
Will mulching feed the lawn?
It returns clippings, and Warwickshire says you may need less fertiliser if you mulch regularly. Neither Warwickshire nor the RHS gives a feed rate you can deduct from a bag of lawn food. Short, dry, regular cuts are the condition. Keep diseased material off the lawn.
Why did the box stay empty?
In these reviews the plug was often still in the chute. Ryobi mowers can arrive with the plug fitted. One Litheli owner had to remove a plastic guard before clippings reached the box. Take the battery out, then inspect the chute, before you decide the collector is faulty.
Which listings cannot offer the choice?
The Swift states mulch and does not state a bag. The WG779E, the Yard Force and the Litheli do not state mulch. The Einhell’s side-discharge bullet and its highlight do not agree, so do not shop it as a settled switch. The Yard Force roller is a stripe feature, not a plug.

Related pages

Cordless mulching lawn mower buying guide

Best cordless mulching lawn mower

Cordless mulching lawn mower

How to mulch mow without clumps or an empty grass box

Small garden cordless mulching mower: 22 cm or 33 cm

Sources

Mulching practice is the RHS and Warwickshire County Council. Noise limits are SI 2001/1701 Schedule 3 and the noise-test pointer in SI 2025/1073. Supply duties are the Supply of Machinery (Safety) Regulations 2008. Battery mowers are in the WEEE scope note. Prices, stars and conflicts are the amazon.co.uk captures dated 22 October 2026. Last checked 22 October 2026.

  1. RHS, lawn mowing (retrieved 22 October 2026)
  2. RHS, drought care for lawns (retrieved 22 October 2026)
  3. Warwickshire County Council, mulch mowing (retrieved 22 October 2026)
  4. GOV.UK, noise emission from outdoor equipment (retrieved 22 October 2026)
  5. SI 2001/1701 Schedule 3, lawnmower noise limits (retrieved 22 October 2026)
  6. SI 2025/1073, electric pedestrian mower noise methods (retrieved 22 October 2026)
  7. GOV.UK, Supply of Machinery (Safety) Regulations 2008 (retrieved 22 October 2026)
  8. GOV.UK, equipment covered by the WEEE regulations (retrieved 22 October 2026)