Lawn moss killer or patio cleaner
Updated: October 2026
The lawn is green in the shade of the fence, the slabs are green in the joints, and one bottle looks as if it could do both. It cannot. A lawn moss killer or patio cleaner is a choice of surface, not a choice of which brand sounds stronger. Iron treatments blacken moss in grass and stain paving when they spill. Patio biocides are written for stone, concrete and similar hard surfaces, and they are not a lawn feed. This page is that versus, using the products in the [moss remover comparison](/hub/weed-control/moss-remover). How you then time the application is on [how to use a moss killer](/hub/weed-control/moss-remover/sub/moss-remover-how-to-use). The Products Compared editorial team compared the amazon.co.uk listings captured on 19 October 2026 with RHS lawn advice and the Westland fact sheet. We did not stain a patio on purpose. If you buy through our links, a qualifying purchase can earn us a commission at no extra cost to you.
The lawn is green in the shade of the fence, the slabs are green in the joints, and one bottle looks as if it could do both. It cannot.
The lawn is green in the shade of the fence, the slabs are green in the joints, and one bottle looks as if it could do both. It cannot. A lawn moss killer or patio cleaner is a choice of surface, not a choice of which brand sounds stronger. Iron treatments blacken moss in grass and stain paving when they spill. Patio biocides are written for stone, concrete and similar hard surfaces, and they are not a lawn feed. This page is that versus, using the products in the moss remover comparison. How you then time the application is on how to use a moss killer. The Products Compared editorial team compared the amazon.co.uk listings captured on 19 October 2026 with RHS lawn advice and the Westland fact sheet. We did not stain a patio on purpose. If you buy through our links, a qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Belongs on | Keep it off | What to expect | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Wet & Forget Wet & Forget 5 L | Slabs, decking, paving | The lawn | Leave-on cleaner, slow | 8.8 | about £29.89 | View offer |
| Best value |  HG HG algae and mould remover 1 L | Paving, paths, masonry | A lawn drench | Overspray line is not a turf treatment | 8.6 | about £8.35 | View offer |
| Alternative |  Westland Westland Moss Master | Grass | Patio and paths | Iron can blacken moss and stain slabs | 7.4 | about £11.10 | View offer |
On this page
Lawn moss killers stay on the grass
If the moss is in the sward, you are in lawn territory. The Royal Horticultural Society treats that as a lawn problem: you may leave the moss, you may scarify, and if you use iron you use it inside an approved mosskiller. Household acids are rejected on grass. In this set the only product that is actually a lawn treatment is Westland Moss Master, at about £11.10 for a 3.62 kg box titled 80 m², with 3.7 from 77 reviews. The fact sheet is for lawns, from March to September. The bullets claim no black moss and no staining of paths. That second claim is a warning. Paths are mentioned so you do not mark them, not so you treat them.
Iron is why the warning exists. Ferrous-sulphate mosskillers blacken moss, and G212 treats that blackening as expected on the lawn. The same iron discolours paving if it sits there. Ferromex, MAPP 16895, is not in this set, and its label says wash spills off paving. Do not copy its dose onto Moss Master. Do copy the caution: granules on sandstone or concrete get washed off. Reviewers of Moss Master are split between no black lawn, and black spots, scorch, or moss still present. None of that makes the box a patio cleaner.
The coverage title is a lawn-planning problem, not a paving one. At the fact sheet's moss rate of 100–150 g/m², 3.62 kg covers roughly 24–36 m², not the titled 80 m². The 80 m² figure lines up nearer the bottom of the feed rate. Under-dosing the lawn will not be fixed by scattering the rest on the path.
Patio cleaners stay off the lawn
If the moss is on the slabs, you want a hard-surface product or a brush, and you keep it off the grass. Wet & Forget, HG and Patio Blast are the hard-surface liquids in this comparison. Wet & Forget at about £29.89 is a 5 L concentrate of benzalkonium chloride, mixed 1:5, for mould, lichen and algae on patios, paving, decking and similar surfaces. Reviewers use it on moss. The UK brand page is a hard-surface method. It is not a lawn feed, and spraying the grass because the patio meets the lawn edge is how you scorch a strip of turf for the sake of the last joint. The listing is 4.4 from 28,636 reviews, which is evidence about hard surfaces, not about ryegrass.
HG at about £8.35 is a 1 L biocide concentrate for algae and mould on paving, paths, masonry and fences, with 4.3 from 412 reviews. The bullets say surrounding grass and plants are safe when it is diluted correctly. That sentence means overspray, carefully diluted, is less likely to damage the edge. It does not mean you can water the lawn with HG to kill moss in the turf. Patio Blast at about £16.99 is named for paths, drives and decking, spray-and-leave, 4.0 from 112 reviews. The active is not in the scrape. Nothing in the listing makes it a lawn product. A reviewer who diluted it 3:1 for flagstones was still on flagstones.
Resolva Moss Killer, about £8.99 and 4.1 from 71 reviews, does not settle the question. The coverage field says 10 m². The active and the surface are not in the scrape, and one reviewer said the listing conflicted with the bottle. Until you read that bottle, Resolva is not evidence for either side. Only the Wet & Forget listing here names benzalkonium chloride. An orange stain on sandstone is the known behaviour of iron on paving, not a test we ran on these ASINs.
When to choose which
Choose Moss Master, or another approved lawn mosskiller read from its own label, when the moss is in the grass and you have decided a chemical is worth it. Choose a hard-surface liquid when the moss is on slabs, a drive, decking or a path, and you can wait. Inside that liquid group, Wet & Forget is the one to leave on a large area, and HG is the smaller, cheaper concentrate, at about £8.35 against about £29.89. Choose a brush when the growth is only in the cracks and you want those cracks clear the same day. The Mitclear, Sbestily and Dustpan brushes, and the Ark Mat if you want 400 W, are that third path. They are neither a lawn feed nor a biocide. They also do not replace a lawn treatment if the turf itself is mossy a metre in from the edge.
The recommendation is the surface. Lawn growth leads to a lawn product. Slab growth leads to a hard-surface product or a brush. The swap to avoid is Moss Master on the patio, or Wet & Forget and HG on the grass. If you have both, buy both kinds, or brush the joints and treat only the lawn. Price is the second clause: the lawn box is about £11.10, patio liquids run from about £8.35 for HG to about £29.89 for Wet & Forget, and a manual brush is about £12 unless you move up to the Ark Mat at about £55.95. Pets and runoff are on is moss killer safe for dogs.
If the lawn and the slabs are both green
Moss only in the joint, with clean grass beside it, is a brush or a patio liquid on the joint, kept off the turf. Moss only in the grass is a lawn job, with spills washed off the slabs. If both are green, treat them on separate days rather than from one watering can.
The buying guide orders the four types if you have not chosen one. Do not borrow the Moss Master 80 m² title as a patio rate, and do not treat a weedy crack beside a healthy lawn as a reason to spread granules.
Common questions
Can I use lawn moss killer on the patio?
No. Moss Master is a lawn box. Iron mosskillers stain paving if they are left on it. The bullets that mention paths are telling you not to stain them. If granules land on the slabs, wash them off. A wire brush or a patio liquid is the product for the joint itself.
Can I use Wet & Forget on the grass?
No. Wet & Forget is a hard-surface cleaner, diluted 1:5 and left. It is not a lawn fertiliser and not an approved way to kill moss in turf. HG's line about plants applies when the product is diluted and used as a path treatment, not as a lawn drench. Patio Blast is named for paths, drives and decking.
Why do patios go orange or brown after a lawn treatment?
Iron from a ferrous-sulphate mosskiller discolours paving. Labels such as Ferromex, which is not in this set, tell you to wash spills off immediately. This page has not run a stain test on Moss Master. The practical step is still to keep granules on the grass and to rinse any that reach the slabs before they sit.
Which products in this comparison are lawn-only?
Only Westland Moss Master. Everything else is a hard-surface liquid or a brush, except Resolva, whose surface is not stated in the scrape. If you need a second lawn product, it is not in this table. Read the label of whatever other mosskiller you buy, and do not borrow Moss Master's 80 m² title as its rate.
What if the moss is only in the cracks, not the lawn?
Treat the cracks and leave the grass alone. A manual brush such as the Mitclear at about £11.89 clears the joint today. A patio liquid can be used on the joint if you keep it off the turf and you can wait. You do not need Moss Master for a weedy crack beside a healthy lawn.
Does Resolva settle the question?
It does not. The listing is a 1 L moss killer with a 10 m² claim, 4.1 from 71 reviews, and no active or surface in the scraped fields. A reviewer said the listing and the bottle disagreed. The label on the pack you are holding is the only reliable split between lawn and patio for that product.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Updated October 2026.
- RHS: Moss in lawns (retrieved October 2026)
- RHS: Algae, lichens, liverworts and moss on hard surfaces (retrieved October 2026)
- HSE: Pesticides in the garden and home (retrieved October 2026)
- HSE: G212 ferrous sulphate label phrases (retrieved October 2026)
- HSE: Biocides overview (retrieved October 2026)
- Westland Moss Master fact sheet (retrieved October 2026)
- Wet & Forget UK: mould, lichen and algae remover (retrieved October 2026)
- amazon.co.uk listings, 19 October 2026, twelve ASINs in this set (retrieved October 2026)