Lawn & garden
Mo Bacter Organic Lawn Moss Killer & Fertiliser dupe
Why pay around £38.00 for Mo Bacter? The bulk active is Sulphate of potash (0-0-50) — 76% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Mo Bacter Organic Lawn Moss Killer & Fertiliser
20 kg bag · £38.00 typical snapshot
Organic compost and nitrogen/phosphorus base (5-5-20)
2 · Active
Potassium oxide (potash) with Bacillus subtilis
20% on the label
7778-80-5K2SO4
Bulk Sulphate of potash (0-0-50)
3 · Mix
20 g/m²
£0.04 per working litre · 76% less than the shelf pack
- Active
- Potassium oxide (potash) with Bacillus subtilis
- CAS
- 7778-80-5
- Dupe
- Sulphate of potash (0-0-50)
- Saving
- 76% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“Destroys moss without leaving black dead debris”
The chemical reality
The moss dies because of high potash, not a magic organic patent. Sulphate of potash (0-0-50) supplies the same K2O without iron staining; a cheap Bacillus or compost-tea inoculant does the digestion step. A 20 kg 5-5-20 bag is mostly filler next to 10 kg of 50% K2O.
Active vs filler
20% Potassium oxide (potash) with Bacillus subtilis · 80% carrier / filler — Organic compost and nitrogen/phosphorus base (5-5-20)
- Typical retail
- £38.00
- 20 kg bag
- Estimated active cost
- £14.80
- Scaled from bulk £18.50 / 10 kg
- Indicative markup
- 2.6×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 20 kg bag pack of Mo Bacter Organic Lawn Moss Killer & Fertiliser typically retails around £38.00 in lawn & garden. That is a UK shelf-price snapshot for the maths on this page — not a live shop quote or a manufacturer RRP. Listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: Destroys moss without leaving black dead debris; Naturally digests dead moss using beneficial bacteria; and Will not stain stone paving or decorative aggregate.
The catch: The moss dies because of high potash, not a magic organic patent. Sulphate of potash (0-0-50) supplies the same K2O without iron staining; a cheap Bacillus or compost-tea inoculant does the digestion step. A 20 kg 5-5-20 bag is mostly filler next to 10 kg of 50% K2O.
- “Destroys moss without leaving black dead debris”
- “Naturally digests dead moss using beneficial bacteria”
- “Will not stain stone paving or decorative aggregate”
Proprietary Blend & Dosage Breakdown
The labelled active is Potassium oxide (potash) with Bacillus subtilis at 20%. Everything else in the pack is organic compost and nitrogen/phosphorus base (5-5-20).
At 20% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 50% Sulphate of potash (0-0-50), mixed to 20 g/m².
- Labelled active
- Potassium oxide (potash) with Bacillus subtilis
- 20%
- Carrier
- Organic compost and nitrogen/phosphorus base (5-5-20)
- Retail pack
- 20 kg bag · £38.00
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Sulphate of potash (0-0-50) at 50% bulk. Indexed as CAS 7778-80-5, formula K2SO4. Buy it as 10 kg for around £18.50 from Amazon UK.
Working strength: 20 g/m². Indicative cost £0.04 per diluted litre — 76% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Wear gloves. Apply 20 g per m² of soluble sulphate of potash — broadcast dry and water in, or dissolve at 20 g/L in a watering can.
- A 10 kg bag covers about 500 m². That is more potassium oxide than a 20 kg 5-5-20 lawn bag, without ferrous sulphate staining on stone.
- Water afterwards with an aerated compost tea or a broad-spectrum Bacillus lawn inoculant if you want the organic-matter digestion step.
- Keep off ponds. Store dry.
Dilution recipe
10 L bucket
Working strength 20 g/m². Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
200 grams
Sulphate of potash (0-0-50)
Water
10 litres
Carrier / diluent
0% concentrate · 100% water by working volume (solids are dissolved into the water share).
Required PPE
Loading calculator…
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedMo Bacter | Raw active dupeDupeStack |
|---|---|---|
| Product | Organic Lawn Moss Killer & FertiliserAmazon UK search — listing, not a confirmed seller | Sulphate of potash (0-0-50) |
| Pack / unit | 20 kg bag · £38.00 | 10 kg · £18.50 |
| Active | Potassium oxide (potash) with Bacillus subtilis at 20%Carrier: Organic compost and nitrogen/phosphorus base (5-5-20) | 50% bulkK2SO4 |
| CAS number | Not disclosed on pack | 7778-80-5 |
| Working strength | Ready-to-use pack | Dilute 20 g/m² |
| Cost per litre | £38.00 / pack | £0.04 / L mixed from bulk |
| Headline saving | Baseline | 76% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene) |
Active ingredient and cheaper alternative — FAQ
What is the active ingredient in Mo Bacter?
Mo Bacter Organic Lawn Moss Killer & Fertiliser is labelled as Potassium oxide (potash) with Bacillus subtilis at 20%. The carrier is Organic compost and nitrogen/phosphorus base (5-5-20). Pack size: 20 kg bag. The bulk equivalent we index is Sulphate of potash (0-0-50) (CAS 7778-80-5).
Is Sulphate of potash (0-0-50) safe on lawns?
Used at the listed working strength (20 g/m²), the dupe is the same chemistry as the branded pack for lawns, beds and pots. That is not a blanket all-clear: read the supplier SDS, wear the listed PPE, keep acids away from hypochlorite, and follow UK HSE/COSHH rules. Wellness teardowns are supplements, not medicines.
Is there a cheaper alternative to Mo Bacter Organic Lawn Moss Killer & Fertiliser?
Yes. The bulk equivalent is Sulphate of potash (0-0-50) (CAS 7778-80-5). Indicative saving 76% per working litre versus a pack that typically retails around £38.00. Working strength: 20 g/m². Live shop prices move.
How do you mix the Organic Lawn Moss Killer & Fertiliser dupe stack?
Wear gloves. Apply 20 g per m² of soluble sulphate of potash — broadcast dry and water in, or dissolve at 20 g/L in a watering can. A 10 kg bag covers about 500 m². That is more potassium oxide than a 20 kg 5-5-20 lawn bag, without ferrous sulphate staining on stone. Water afterwards with an aerated compost tea or a broad-spectrum Bacillus lawn inoculant if you want the organic-matter digestion step. Keep off ponds. Store dry.
DupeStack provides chemical concentration data and educational mixing guides only. Wellness pages compare food supplements, not medicines or prescribed treatments. Always review the supplier Safety Data Sheet (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Mixing and storage are at your own risk. Some links are affiliate advertisements (Amazon Associates, eBay Partner Network, and Awin when those programmes are live). Commissions do not change listed concentrations or calculator output.
Related guides
Lawn guide
Weedkillers decoded: glyphosate vs triclopyr — paths, brambles and lawn
Pathclear RTU, Resolva Xpress pelargonic, Doff mecoprop-P, Weedol Lawn MCPA three-way, SBK brushwood killer and ferric slug bait use different actives. Match the molecule to the weed — and never swap without reading the label.
Lawn guide
Garden tonics decoded: seaweed, chelated iron, Epsom and rooting powder
Kelp extract, Fe-EDDHA, Epsom salts, IBA rooting powder and foliar soap are not NPK bags. Match the deficiency or the cutting — then buy the bulk salt, not the sachet.
Lawn guide
Lawn moss vs a nitrogen green-up — ferrous sulphate is not sulphate of ammonia
Evergreen 4-in-1 and lawn sands use iron to blacken moss. Sulphate of ammonia is 21% N for colour. Do not treat a feed box as a moss killer — or a moss killer as Growmore.
More teardowns
Lawn & garden
Miracle-Gro Organic Liquid Seaweed
Miracle-Gro
- Retail pack
- £13.501 litre
- Raw active
- Soluble Ascophyllum nodosum kelp powder84775-78-0
A watered-down cold-pressed kelp extract. Soluble Ascophyllum nodosum powder is the same crop, sold by the kilogram to hydroponic growers, at a fraction of the bottled price.
Lawn & garden
Evergreen Complete 4-in-1 Lawn Feed & Moss Killer
Evergreen
- Retail pack
- £24.00100 m² box
- Raw active
- Agricultural soluble iron(II) sulphate heptahydrate7782-63-0
The moss-blackening punch is ferrous sulphate — the same agricultural iron used on bowling greens. The 4-in-1 box is mostly filler, NPK dust and a brand. Buy the salt.
Lawn & garden
Growmore Garden Fertiliser
Growmore
- Retail pack
- £9.504 kg
- Raw active
- Agricultural NPK 7-7-7 compound fertiliser66455-26-3
7-7-7 is a commodity NPK blend. The cardboard box is a portioned sack of agricultural compound fertiliser. Buy it by the 25 kg bag from a merchant, not 4 kg at a time from a garden centre.
£28.50Save 76% / L
Indicative DIY stack