Lawn & garden
Vitax Q4 All Purpose Plant Food dupe
Why pay around £10.99 for Vitax? The bulk active is Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack) — 45% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Vitax Q4 All Purpose Plant Food
2.5 kg box · £10.99 typical snapshot
Organic base and pellet binder
2 · Active
Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces
26% on the label
66455-26-3N + P2O5 + K2O + MgO
Bulk Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack)
3 · Mix
140 g/m²
£2.40 per working litre · 45% less than the shelf pack
- Active
- Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces
- CAS
- 66455-26-3
- Dupe
- Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack)
- Saving
- 45% / 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
“The premier fertiliser for flowers, roses, fruit and vegetables”
The chemical reality
Q4 is a specific 5.3-7.5-10 organo-mineral with magnesium — not Growmore 7-7-7 and not Q4 HN (10.5-7.5-10.2). The garden box is a portioned sack. The same analysis is sold as a 20 kg professional bag.
Active vs filler
26% Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces · 74% carrier / filler — Organic base and pellet binder
- Typical retail
- £10.99
- 2.5 kg box
- Estimated active cost
- £6.00
- Scaled from bulk £48.00 / 20 kg
- Indicative markup
- 1.8×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 2.5 kg box pack of Vitax Q4 All Purpose Plant Food typically retails around £10.99 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: The premier fertiliser for flowers, roses, fruit and vegetables; Trusted by professional growers; and One handful feeds plants for weeks.
The catch: Q4 is a specific 5.3-7.5-10 organo-mineral with magnesium — not Growmore 7-7-7 and not Q4 HN (10.5-7.5-10.2). The garden box is a portioned sack. The same analysis is sold as a 20 kg professional bag.
- “The premier fertiliser for flowers, roses, fruit and vegetables”
- “Trusted by professional growers”
- “One handful feeds plants for weeks”
Proprietary Blend & Dosage Breakdown
The labelled active is Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces at 26%. Everything else in the pack is organic base and pellet binder.
At 26% 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 26% Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack), mixed to 140 g/m².
- Labelled active
- Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces
- 26%
- Carrier
- Organic base and pellet binder
- Retail pack
- 2.5 kg box · £10.99
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack) at 26% bulk. Indexed as CAS 66455-26-3, formula N + P2O5 + K2O + MgO. Buy it as 20 kg for around £48.00 from Amazon UK.
Working strength: 140 g/m². Indicative cost £2.40 per diluted litre — 45% 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 a dust mask; Q4 powder is gritty. Apply on a still day and water in if the soil is dry.
- Flowers and vegetables: 140 g per m² as a base dressing before planting; 70 g/m² as a top dress once or twice in the season. Roses: 140 g/m² in spring.
- A 20 kg sack at 140 g/m² covers about 140 m². The 2.5 kg box at the same rate is about 18 m².
- Do not confuse with Q4 HN. Store dry. This is a feed, not a pesticide — keep off ponds.
Dilution recipe
5 L sprayer
Working strength 140 g/m². Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
14,000 grams
Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack)
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 brandedVitax | Raw active dupeDupeStack |
|---|---|---|
| Product | Q4 All Purpose Plant FoodAmazon UK search — listing, not a confirmed seller | Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack) |
| Pack / unit | 2.5 kg box · £10.99 | 20 kg · £48.00 |
| Active | Organo-mineral NPK 5.3-7.5-10 plus 3% MgO and traces at 26%Carrier: Organic base and pellet binder | 26% bulkN + P2O5 + K2O + MgO |
| CAS number | Not disclosed on pack | 66455-26-3 |
| Working strength | Ready-to-use pack | Dilute 140 g/m² |
| Cost per litre | £10.99 / pack | £2.40 / L mixed from bulk |
| Headline saving | Baseline | 45% 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 Vitax Q4 HN the same as garden-centre Q4?
No. Garden Q4 and the professional powder are 5.3-7.5-10 plus about 3% magnesium oxide. Q4 HN is a different, higher-nitrogen granular (around 10.5-7.5-10.2). Buy the 5.3-7.5-10 sack, not HN, if you want the same feed as the 2.5 kg box.
Is Q4 just Growmore in a nicer box?
No. Growmore is inorganic 7-7-7. Q4 is a slower organo-mineral at 5.3-7.5-10 with magnesium and traces, originally a John Innes base fertiliser. The stack is a 20 kg bag of that analysis, not a 25 kg bag of 7-7-7.
How do you mix the Q4 All Purpose Plant Food dupe stack?
Wear gloves and a dust mask; Q4 powder is gritty. Apply on a still day and water in if the soil is dry. Flowers and vegetables: 140 g per m² as a base dressing before planting; 70 g/m² as a top dress once or twice in the season. Roses: 140 g/m² in spring. A 20 kg sack at 140 g/m² covers about 140 m². The 2.5 kg box at the same rate is about 18 m². Do not confuse with Q4 HN. Store dry. 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.
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£62.00Save 45% / L
Indicative DIY stack