Scarifiers
Scarifying is the one lawn job where the machine is less important than the setting. Every scarifier here adjusts its depth, and the range is published on five of the six: from six millimetres above the sward to fifteen below it. Set shallow it takes out the thatch that is strangling the grass; set deep it tears the lawn apart. This guide is the depth figures, and the order the rest of the work has to happen in.
Between the green grass you can see and the soil underneath it, there is a layer of dead stems, old clippings, roots and moss — matted, springy, and increasingly waterproof as it thickens.
That layer is thatch, and a thin one is normal and useful. A thick one is the reason a lawn looks tired without any obvious problem: water runs off it rather than through it, seed sown on top of it never reaches soil, and the grass roots into the thatch instead of into the ground.
A scarifier drags steel blades through it and pulls it out.
Five of these six publish a depth range, and they run:
−12 to +6 mm, on two machines. −15 to +5 mm. −15 to 0 mm. Four depths, on another. And one publishes an adjustable depth with no figures.
Read those properly, because the sign matters.
Positive is above the sward — the roller lifted clear, which is the transport and aerating position.
Zero is just touching.
Negative is into the surface, and −12 or −15 mm is a long way in.
The single most common way a lawn is ruined is a scarifier set to its deepest setting on the first pass.
At −12 mm the blades are not pulling thatch out. They are cutting into the soil, taking the crowns of the grass plants with the dead material, and what comes off is not a bag of thatch but a bag of lawn.
The method is boring and it works:
Set to zero. Take one pass. Look at what is in the bag.
Go down 3 mm. Take another pass at right angles to the first. Look again.
Stop when the bag fills with brown and not green. That is the depth for that lawn, that year, and it will be shallower than you expect.
A domestic lawn scarified annually rarely needs more than a few millimetres. The deep settings exist for a lawn that has not been touched in a decade, and that lawn needs reseeding afterwards whatever happens.
Four of these six carry two rollers: a scarifying roller with blades, and an aerating roller with sprung steel tines.
Two publish the counts precisely — 20 blades and 24 tines, on both — and two publish blades only.
The distinction between them is real:
Blades cut. They slice vertically through the thatch layer and lift it.
Tines comb. They drag through the surface and pull loose material out without cutting into the sward.
For an annual tidy on a lawn in reasonable condition, the tine roller is often the right choice and almost nobody uses it — because on two of these machines the roller change is the thing that decides it. One publishes a tool-free change; the other says the rollers are easily interchangeable. A roller swap that needs a spanner happens once.
Scarifying is step three of five, and doing it out of order wastes it.
One: mow, short. Lower than usual, and collect. A scarifier cannot reach the thatch through long grass, and long grass wraps the roller.
Two: kill the moss, if there is moss. Moss in a thatch layer comes out with it — and moss treated with iron and then scarified two weeks later comes out far more completely. This site’s moss shelf covers the products and the one caution that matters: iron stains paving permanently.
Three: scarify. Shallow, twice, at right angles, collecting everything.
Four: overseed. This is the step people skip and it is the one that makes the difference. Scarifying leaves bare soil, and bare soil in a lawn is where the next weed germinates. It is also the only condition in which grass seed works — seed that lands on existing turf never reaches ground. The seed shelf on this site publishes rates of 20 to 30 g/m², and a scarified lawn is the one day of the year when overseeding actually takes.
Five: feed, and do not let it dry out. Germinating seed must not dry out once. Two weeks of attention after scarifying is worth more than the scarifying was.
Weight.
Not one of these six states it, and on a machine that has to be pushed into a lawn while resisting the drag of blades in soil, it is the figure that decides how hard the job is.
Two of them are petrol, at 182 and 212 cc; one is petrol at 79 cc; two are 2000 W mains; one is cordless and supplied as a bare tool. Every one of those is a different amount of machine to push, and none of them says how much.
32 cm, 1500 W, 16 blades + 36 claws, 4 depths, 30 L
Both cartridges in the box — 16 blades and 36 aerator claws — on a 1500 W mains machine with a 30-litre catcher.
Best for: A small to medium lawn being scarified for the first time, where both operations will be tried
40 cm, 2000 W, 20 blades + 24 sprung tines, −12 to +6 mm, 55 L
Tool-free roller changes, a −12 to +6 mm depth range, a 55-litre bag, and the option of working with no bag at all.
Best for: A large, genuinely thatched lawn where the first pass will be run without the bag
40 cm, 2000 W, 20 blades + 24 tines, −12 to +6 mm, 55 L
A 2000 W machine with a stated depth range of −12 to +6 mm, a 55-litre bag and both rollers — sold as one of three models in a range.
Best for: A large lawn with real thatch, where the depth needs setting rather than guessing
Cordless, bare tool, 2-in-1, 4 heights, 40 L bag
The only cordless machine on this shelf, supplied without pack or charger, with a curved base stated to reduce pushing resistance.
Best for: A medium lawn away from a socket, in a shed that already holds this maker’s packs
38 cm, 1.4 kW / 79 cm³, 14 blades + 48 tines, −14 to +6 mm, 55 L
A 79 cm³ petrol machine with 14 blades or 48 sprung tines, a −14 to +6 mm depth range and a 55-litre catcher.
Best for: A large lawn out of reach of a socket, scarified properly once or twice a year
40 cm, 182 cm³ four-stroke, 32 swinging blades, −15 to 0 mm, 40 L
Thirty-two free-swinging blades on a 182 cm³ four-stroke, with a depth range that stops at ground level and an easy-start engine.
Best for: A large, stony or rough lawn where a fixed blade would find something hard
Shallow — a few millimetres into the surface, not into the soil. The published ranges here run to −12 and −15 mm, and those settings are for a contractor renovating a ruined lawn, not for an annual tidy. Start at zero, take one pass, look at what came out, and go deeper only if the thatch is still there.
Scarifying pulls dead material out of the mat between the green grass and the soil. Aerating makes holes in the soil below it. Four of these six machines do both with interchangeable rollers — blades for scarifying, sprung tines for aerating — and they are different jobs done at different depths.
When the lawn is growing strongly enough to recover, which is after the first two or three cuts rather than at the first warm weekend. A scarified lawn looks worse before it looks better, and it needs several weeks of growing weather to close the gaps. On a cold late spring, waiting a fortnight is better than scarifying early.
Yes, and it is most of the work. Five of these six publish a catcher volume — 30, 40, 40, 55 and 55 litres — and a scarified lawn produces far more material than any of them holds in one pass. Whatever is left on the surface becomes thatch again.
For : A small to medium lawn being scarified for the first time, where both operations will be tried
Main strength : Both cartridges supplied, with the blade and claw counts given for each
Main limitation : Four depth positions but no range — so what it can actually reach is unknown
For : A large, genuinely thatched lawn where the first pass will be run without the bag
Main strength : Roller changes stated as tool-free, on a job that otherwise means finding a spanner
Main limitation : No weight published
For : A large lawn with real thatch, where the depth needs setting rather than guessing
Main strength : A published depth range with ground level at zero — the figure that decides the job
Main limitation : The listing covers three models at once, so width and wattage depend on the variant chosen
For : A medium lawn away from a socket, in a shed that already holds this maker’s packs
Main strength : The only cordless machine on a shelf otherwise made of cables and engines
Main limitation : No pack and no charger in the box, so the listed price is not the price
For : A large lawn out of reach of a socket, scarified properly once or twice a year
Main strength : Every headline figure published: power, displacement, width, both roller counts, depth range and catcher
Main limitation : A petrol engine used twice a year means fuel that has to be managed between seasons
For : A large, stony or rough lawn where a fixed blade would find something hard
Main strength : Free-swinging blades, which survive a stone rather than stopping on it
Main limitation : No aerating cartridge stated — the blades do both jobs by depth alone
Head-to-heads already published between two models from this guide or this aisle.
The models here come from the catalogue of this site. Specifications are those published by the manufacturer and on the Amazon product page; prices are what Keepa reported on the date below, and both move. The ranking uses declared specifications, the balance of stated strengths and limitations, and price. No product on this site has been physically tested, and nothing here claims otherwise.
Last checked on
A mower gets bought when the grass is already too long, which is the worst possible moment to weigh up a price: demand on this shelf climbs from March and drops away after July, so a price struck through in May tells you nothing whatever about what the same reference cost in October. UniverTrack keeps a week-by-week record for each retailer, so a cut price can be set against one somebody really paid rather than one composed for the banner — and it says when ordering is genuinely the moment.
