Lawn & garden
Growmore Garden Fertiliser dupe
Why pay around £9.50 for Growmore? The bulk active is Agricultural NPK 7-7-7 compound fertiliser — 63% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Growmore Garden Fertiliser
4 kg · £9.50 typical snapshot
Granular filler
2 · Active
NPK 7-7-7 compound
21% on the label
66455-26-3N + P2O5 + K2O
Bulk Agricultural NPK 7-7-7 compound fertiliser
3 · Mix
100 g/m²
£0.88 per working litre · 63% less than the shelf pack
- Active
- NPK 7-7-7 compound
- CAS
- 66455-26-3
- Dupe
- Agricultural NPK 7-7-7 compound fertiliser
- Saving
- 63% / 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
“Balanced feed for flowers, fruit, vegetables and lawns”
The chemical reality
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.
Active vs filler
21% NPK 7-7-7 compound · 79% carrier / filler — Granular filler
- Typical retail
- £9.50
- 4 kg
- Estimated active cost
- £3.52
- Scaled from bulk £22.00 / 25 kg
- Indicative markup
- 2.7×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 4 kg pack of Growmore Garden Fertiliser typically retails around £9.50 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: Balanced feed for flowers, fruit, vegetables and lawns; Trusted by British gardeners for generations; and Easy-spread granules.
The catch: 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.
- “Balanced feed for flowers, fruit, vegetables and lawns”
- “Trusted by British gardeners for generations”
- “Easy-spread granules”
Proprietary Blend & Dosage Breakdown
The labelled active is NPK 7-7-7 compound at 21%. Everything else in the pack is granular filler.
At 21% 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 21% Agricultural NPK 7-7-7 compound fertiliser, mixed to 100 g/m².
- Labelled active
- NPK 7-7-7 compound
- 21%
- Carrier
- Granular filler
- Retail pack
- 4 kg · £9.50
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Agricultural NPK 7-7-7 compound fertiliser at 21% bulk. Indexed as CAS 66455-26-3, formula N + P2O5 + K2O. Buy it as 25 kg for around £22.00 from Amazon UK.
Working strength: 100 g/m². Indicative cost £0.88 per diluted litre — 63% 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. Avoid breathing dust; apply on a still day.
- Broadcast 70–100 g per m² around plants or over beds, then water in.
- A 25 kg sack covers roughly 250 m² at 100 g/m².
- Do not pile against stems. Store dry — it cakes when damp.
- This is a feed, not a pesticide. Keep off ponds.
Dilution recipe
5 L sprayer
Working strength 100 g/m². Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
10,000 grams
Agricultural NPK 7-7-7 compound fertiliser
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 brandedGrowmore | Raw active dupeDupeStack |
|---|---|---|
| Product | Growmore Garden FertiliserAmazon UK search — listing, not a confirmed seller | Agricultural NPK 7-7-7 compound fertiliser |
| Pack / unit | 4 kg · £9.50 | 25 kg · £22.00 |
| Active | NPK 7-7-7 compound at 21%Carrier: Granular filler | 21% bulkN + P2O5 + K2O |
| CAS number | Not disclosed on pack | 66455-26-3 |
| Working strength | Ready-to-use pack | Dilute 100 g/m² |
| Cost per litre | £9.50 / pack | £0.88 / L mixed from bulk |
| Headline saving | Baseline | 63% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Ventilation. Use outdoors or with mechanical extraction |
Active ingredient and cheaper alternative — FAQ
Is Growmore the same as Vitax Q4?
No. Growmore is inorganic 7-7-7. Q4 is an organo-mineral at 5.3-7.5-10 with magnesium. Different analysis, different release curve — see the Q4 teardown for the 20 kg sack of that feed.
How much Growmore per square metre?
Broadcast about 70–100 g per m² around plants or over beds, then water in. A 25 kg sack at 100 g/m² covers roughly 250 m². Do not pile against stems.
How do you mix the Growmore Garden Fertiliser dupe stack?
Wear gloves. Avoid breathing dust; apply on a still day. Broadcast 70–100 g per m² around plants or over beds, then water in. A 25 kg sack covers roughly 250 m² at 100 g/m². Do not pile against stems. Store dry — it cakes when damp. This is a feed, not a pesticide. Keep off ponds.
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
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More teardowns
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- Retail pack
- £13.501 litre
- Raw active
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- Retail pack
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- Retail pack
- £6.001 litre
- Raw active
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£36.50Save 63% / L
Indicative DIY stack