Moss killer for lawn or patio
Updated: October 2026
You have moss in the lawn and a green film on the slabs, and one trigger bottle looks as if it should do both. It will not. A moss killer for lawn or patio is two chemistries, and each damages the surface it was not bought for. Lawn iron blackens moss in grass and stains paving. Resolva kills green growth, including grass, and the maker bars it from concrete, tarmac and lawns. This page is that one decision. The [Moss killer comparison](/hub/weed-control/moss-killer) lists all twelve products. The [buying guide](/hub/weed-control/moss-killer/sub/moss-killer-buying-guide) covers weeds and price per square metre as well. The Royal Horticultural Society notes that growth on hard surfaces is a slip risk and that it returns. One clear-up is not a permanent patio. Products Compared editorial team, 16 October 2026. No lab test. A qualifying purchase can earn a commission at no extra cost to you.
You have moss in the lawn and a green film on the slabs, and one trigger bottle looks as if it should do both. It will not.
You have moss in the lawn and a green film on the slabs, and one trigger bottle looks as if it should do both. It will not. A moss killer for lawn or patio is two chemistries, and each damages the surface it was not bought for. Lawn iron blackens moss in grass and stains paving. Resolva kills green growth, including grass, and the maker bars it from concrete, tarmac and lawns. This page is that one decision. The Moss killer comparison lists all twelve products. The buying guide covers weeds and price per square metre as well. The Royal Horticultural Society notes that growth on hard surfaces is a slip risk and that it returns. One clear-up is not a permanent patio. Products Compared editorial team, 16 October 2026. No lab test. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Surface | Stain risk | Season | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Miracle-Gro Miracle-Gro Autumn 80 m² | Lawn only | Iron stains paving | September to November | 8.8 | about £12.48 | View offer |
| Best value |  GREENFORCE Greenforce 4-in-1 15 kg | Lawn only | Treat as a staining risk | Every 4 to 6 weeks | 7.8 | about £30.50 | View offer |
| Alternative |  Resolva Resolva Moss Killer RTU 1 L | Block paving, gravel, decking | Non-staining claim | Not 18 Sep to 1 Apr | 6.8 | about £4.49 | View offer |
On this page
Two jobs, two chemistries
If you can feel soil and grass under the moss, you are on a lawn job. The lawn listings here are the Greenforce bags, Miracle-Gro Mosskill, Complete 4-in-1, Autumn, Moss Master, and a generic iron jerrycan that fails the authorisation check below. They are not patio cleaners. If the moss sits on block paving, gravel or decking, you are on a permeable surface, and Resolva's bullets name those. If the surface is poured concrete or tarmac, Resolva's maker says no, because the spray runs off. Green Gone is the wide hard-surface listing. Path and Drive is the weedkiller that also claims moss. Neither is a lawn feed.
The bank-holiday plan, one bottle for the path and the lawn edge, is the mistake. A title is not the restriction. The sentence that says where the product must not go is the restriction. Read it before you open the spray.
What lawn iron does to paving
Sulphate of iron turns autumn lawn moss black, and it leaves a rusty mark on sandstone, flags and decking. Lawnsmith says the mark does not wash off in any useful way. Marshalls' aftercare guide says avoid ferrous sulphate on paving. If granules land on the stone, brush them up. Do not hose them into the joint. Water carries the iron into the face of the slab.
Miracle-Gro Autumn is the explicit iron listing: iron sulphate, 80 square metres, £12.48, black in seven days, rake after two weeks, September to November. That rake is a lawn step, and it is also when debris gets walked onto the patio. Brush the margin before you water the grass in. The pet line on Autumn and on Complete is children and pets back only after watering in and drying. That water stays on the grass. Mosskill's maker label says wash liquid spills off paving immediately, and that you do not water the foliar spray in. Hosing a scatter of granules is the Marshalls problem, not that liquid instruction. The Greenforce bags print no stain warning. Absence is not a promise. Treat every lawn moss bag here as a staining risk on stone.
The generic 20% ferrous sulphate, 5 litres at £14.97, is not a clever cheap route onto either surface. No MAPP, no reviews and no rate appear in the raw file. RHS says that grade of iron should not kill lawn moss unless it is inside an approved proprietary mosskiller.
What Resolva does to grass and to tarmac
Westland's Resolva page is plain. Permeable surfaces only. Not lawns, because it kills grass. Not concrete or tarmac, because of runoff. Closed from 18 September to 1 April. Agrigem prints MAPP 17100 for the ready-to-use litre. That number is not in the Amazon raw file, so you confirm it on the bottle.
The £4.49 listing matches the permeable half: block paving, gravel and decking, 10 square metres, a non-staining claim, 4.2 from 423 reviews. It does not say lawn. Reviewers mention the winter ban the bullets omit. Amazon says rain-fast in one hour. The maker says rain within 12 hours may weaken the spray. The bottle wins if they clash on the day.
The 3 litre listing with Topline in the brand field is the trap. The title says drives, paths, lawns and roofs. The bullets say block paving, gravel and decking, and that the formula removes grasses, at 10 square metres a litre. A lawn in the title is not permission. Do not spray a roof from that title. This comparison does not recommend it. The price is £25.95 with 3.9 from 23 reviews. The £4.49 litre is the same permeable job without the lawn sentence. The plain Resolva litre at £8.99 states no surface at all. Do not assume it is safe on turf.
Which listing is which
Lawn only: Greenforce 15 kg at £30.50 for 750 square metres, Greenforce 3 kg at £15.25 for 150 square metres, Mosskill at £12 for up to 67 square metres, Complete at £15 for 80 square metres from April to September, Autumn at £12.48 for 80 square metres from September to November, and Moss Master at £11.10 for 80 square metres with a no-rake claim the reviews dispute. The jerrycan is a lawn-shaped title without an authorisation you can see.
Permeable paving: the £4.49 Resolva, with the maker's bans still in force. The 3 litre only if you follow the bullets and ignore lawns and roofs in the title. Paths and drives as a weedkiller that also claims moss: Path and Drive, 3 litres at £18, pelargonic acid, all year, 4.3 from 46 reviews, no square metres and no pet line. Wide hard surfaces, leave on: Green Gone, 5 litres, up to 50 square metres, £12.80, pets once dry, 4.2 from 318 reviews. The raw file has no MAPP, so this page does not call it authorised. It is still not for the lawn.
How you apply the one you chose is the how to use page. Raking black lawn moss is the raking page.
When you have both surfaces
Buy two products. Treat the lawn to a hand's width from the slabs, brush the edge, then water the grass in. Treat permeable joints with Resolva only in its open season, and keep the nozzle off the turf. Do not reach for Resolva on tarmac because the drive is basically a path. The maker has refused that shortcut.
Moss returns on both if shade and water stay. RHS says hard-surface growth comes back, and lawn moss comes back while compaction and drainage stay poor. If the only green is a slippery film on stone, you do not need a 15 kg lawn bag. If the only green is a mat in the turf, you do not need a path spray. The edge where lawn meets slab is where you slow down, not where you mix both products in one can.
Common questions
Can I put lawn moss killer on the patio?
No. Lawn iron stains paving, and Marshalls says keep ferrous sulphate off it. Brush a spill up. Do not wash granules into the joints. A lawn feed, weed and moss bag is for grass. The patio needs a hard-surface product whose label allows that stone.
Will iron stain sandstone?
It can. Lawnsmith records marks that do not wash off, and Marshalls groups ferrous sulphate with products to keep off paving. Flags at a lawn edge are a typical place for a rusty line after an autumn spread. Brush the boundary before you water in.
Can Resolva go on the lawn if the title says lawns?
No. The 3 litre title mentions lawns, and the bullets say the formulation removes grasses. Westland says Resolva moss killer is not for lawns. Follow the maker and the bullets. You will brown the turf you were trying to tidy.
Can Resolva go on tarmac or concrete?
The maker says no. Concrete and tarmac are excluded because the spray runs off. The £4.49 bullets name block paving, gravel and decking. A tarmac drive is outside that list. Runoff into a drain is part of the ban, not a detail you skip if the nozzle is careful.
What is Green Gone for?
A leave-on hard-surface treatment: 5 litres, up to 50 square metres, £12.80, algae, mould and moss, pets once dry, 4.2 from 318 reviews of patios, paving and concrete. It is not a lawn product. The bullets do not name lichen, and the raw file shows no MAPP number. Read the bottle before you treat a wide patio.
What if moss is on both the lawn edge and the slabs?
Use the lawn product on the grass and the hard-surface product on the slabs. Brush iron off the stone before you water the lawn. Keep Resolva off the turf, because it kills grass. The messy edge is where a single bottle does the most damage.
Will one treatment keep the patio clear?
Do not count on it. RHS says growth on hard surfaces returns where water and shade remain. Green Gone claims up to nine months, which is still not a permanent clear surface. Joints that hold damp will green up again. Standing water is the longer job.
Related pages
Sources
Public UK sources from the research digest. Shelf prices and star lines are the amazon.co.uk figures in the display file. Coverage rates are manufacturer claims, not a trial run for this page.
- RHS: moss in lawns (retrieved 16 October 2026)
- RHS: moss on hard surfaces (retrieved 16 October 2026)
- HSE: garden and home pesticides (retrieved 16 October 2026)
- HSE: COPR and moss claims (retrieved 16 October 2026)
- Westland: Resolva moss killer (retrieved 16 October 2026)
- Westland: Moss Master (retrieved 16 October 2026)
- Miracle-Gro Mosskill label (retrieved 16 October 2026)
- Marshalls: paving aftercare (retrieved 16 October 2026)