Lawn & garden
Westland Sulphate of Potash dupe
Why pay around £5.99 for Westland? The bulk active is Agricultural potassium sulphate (sulphate of potash, 0-0-48) — 70% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Westland Sulphate of Potash
1.5 kg box · £5.99 typical snapshot
None (prills; some lots include potassium hydrogen sulphate)
2 · Active
Potassium sulphate
48% on the label
7778-80-5K2SO4
Bulk Agricultural potassium sulphate (sulphate of potash, 0-0-48)
3 · Mix
35 g/m² around fruit and flowers (Westland handful band)
£0.04 per working litre · 70% less than the shelf pack
- Active
- Potassium sulphate
- CAS
- 7778-80-5
- Dupe
- Agricultural potassium sulphate (sulphate of potash, 0-0-48)
- Saving
- 70% / 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
“Bigger, healthier fruit and flowers”
The chemical reality
Westland’s 1.5 kg box is potassium sulphate (K₂SO₄, CAS 7778-80-5) at about 0-0-48 — potash only, not nitrate of potash (KNO₃, 13-0-46) and not Tomorite. A 25 kg agricultural sack is the same salt. Some bags carry potassium hydrogen sulphate and an eye-damage warning — read the SDS.
Active vs filler
48% Potassium sulphate · 52% carrier / filler — None (prills; some lots include potassium hydrogen sulphate)
- Typical retail
- £5.99
- 1.5 kg box
- Estimated active cost
- £1.50
- Scaled from bulk £26.00 / 25 kg
- Indicative markup
- 4.0×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 1.5 kg box pack of Westland Sulphate of Potash typically retails around £5.99 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: Bigger, healthier fruit and flowers; Fast-acting ready-to-use granules; and NPK 0-0-48 — potash without extra nitrogen.
The catch: Westland’s 1.5 kg box is potassium sulphate (K₂SO₄, CAS 7778-80-5) at about 0-0-48 — potash only, not nitrate of potash (KNO₃, 13-0-46) and not Tomorite. A 25 kg agricultural sack is the same salt. Some bags carry potassium hydrogen sulphate and an eye-damage warning — read the SDS.
- “Bigger, healthier fruit and flowers”
- “Fast-acting ready-to-use granules”
- “NPK 0-0-48 — potash without extra nitrogen”
Proprietary Blend & Dosage Breakdown
The labelled active is Potassium sulphate at 48%. Everything else in the pack is none (prills; some lots include potassium hydrogen sulphate).
Even when the pack is sold as “pure” or ready-to-use, the dose that actually does the work is Potassium sulphate. The rest is how they get it into a bottle you will pick up.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 50% Agricultural potassium sulphate (sulphate of potash, 0-0-48), mixed to 35 g/m² around fruit and flowers (Westland handful band).
- Labelled active
- Potassium sulphate
- 48%
- Carrier
- None (prills; some lots include potassium hydrogen sulphate)
- Retail pack
- 1.5 kg box · £5.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Agricultural potassium sulphate (sulphate of potash, 0-0-48) at 50% bulk. Indexed as CAS 7778-80-5, formula K2SO4. Buy it as 25 kg for around £26.00 from Amazon UK.
Working strength: 35 g/m² around fruit and flowers (Westland handful band). Indicative cost £0.04 per diluted litre — 70% 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 and eye protection — some SOP lots include potassium hydrogen sulphate (serious eye damage). Avoid breathing dust.
- Broadcast about 35 g/m² around the root zone of fruit, tomatoes and flowers, then water in. That is the garden-centre handful rate.
- 25 kg at 35 g/m² covers about 710 m² — more than sixteen 1.5 kg boxes.
- This is potash only (0-0-48). It is not a complete fertiliser, not nitrate of potash, and not a pesticide. Do not mix with lime in the same pass.
Dilution recipe
5 L sprayer
Working strength 35 g/m² around fruit and flowers (Westland handful band). Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
3,500 grams
Agricultural potassium sulphate (sulphate of potash, 0-0-48)
Water
5 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 brandedWestland | Raw active dupeDupeStack |
|---|---|---|
| Product | Sulphate of PotashAmazon UK search — listing, not a confirmed seller | Agricultural potassium sulphate (sulphate of potash, 0-0-48) |
| Pack / unit | 1.5 kg box · £5.99 | 25 kg · £26.00 |
| Active | Potassium sulphate at 48%Carrier: None (prills; some lots include potassium hydrogen sulphate) | 50% bulkK2SO4 |
| CAS number | Not disclosed on pack | 7778-80-5 |
| Working strength | Ready-to-use pack | Dilute 35 g/m² around fruit and flowers (Westland handful band) |
| Cost per litre | £5.99 / pack | £0.04 / L mixed from bulk |
| Headline saving | Baseline | 70% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectaclesVentilation. Use outdoors or with mechanical extraction |
Active ingredient and cheaper alternative — FAQ
Is this the same as Westland nitrate of potash?
No. Nitrate of potash is potassium nitrate (CAS 7757-79-1), 13-0-46 — nitrogen plus potash, and an oxidiser. Sulphate of potash is K₂SO₄ (CAS 7778-80-5), typically 0-0-48, no nitrogen. Different salt, different job.
Will this replace Tomorite?
Not as a complete tomato bottle. Tomorite-style feeds are dilute NPK (around 4-3-8) plus seaweed. Sulphate of potash is potash only — useful when fruit is set and you already have nitrogen from elsewhere. See the Tomorite and nitrate-of-potash teardowns.
How do you mix the Sulphate of Potash dupe stack?
Wear gloves and eye protection — some SOP lots include potassium hydrogen sulphate (serious eye damage). Avoid breathing dust. Broadcast about 35 g/m² around the root zone of fruit, tomatoes and flowers, then water in. That is the garden-centre handful rate. 25 kg at 35 g/m² covers about 710 m² — more than sixteen 1.5 kg boxes. This is potash only (0-0-48). It is not a complete fertiliser, not nitrate of potash, and not a pesticide. Do not mix with lime in the same pass.
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.
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£38.00Save 70% / L
Indicative DIY stack