Read the three numbers
N–P–K on a UK bag is nitrogen, phosphate (P₂O₅) and potash (K₂O) by percentage. They tell you the job: leafy push (higher N), roots and flowering (P and K), ripening and firm growth (low N, high PK).
Brand names do not change the salt. If two boxes share an analysis, the cheaper bulk sack with the same numbers is the same feed.
Common garden-centre analyses
Growmore-style 7-7-7 — general granular. Miracle-Gro liquid powder family — often ~20-20-20. Tomorite-style tomato feeds — lower N, higher K. Chempak Formula 8 — 12.5-25-25 for mature growth. Westland nitrate of potash — 13-0-46 soluble (nitrogen plus potash). Westland sulphate of potash — 0-0-48, potash only, not an oxidiser and not a complete NPK. Bone meal is slow organic phosphate (about 3.5-18-0) — not Fish, Blood & Bone and not mineral superphosphate.
Moss killers that rely on iron are a different story (ferrous sulphate) — do not treat them as a feed swap. Garden lime is calcium carbonate (plus dolomite) to raise pH — the opposite of iron or sulphate of ammonia, and not a feed analysis. See the Westland Garden Lime teardown.
Weigh per square metre
Granular rates are grams per m², not ‘a handful’. Use the teardown mixing spec and a kitchen scale once, then stick to that scoop. Keep soluble iron off pale stone if you want to avoid rust stains.
FAQ
- Is Vitax Q4 the same as Growmore?
- No. Growmore is inorganic 7-7-7. Garden Q4 is an organo-mineral around 5.3-7.5-10 with magnesium. Q4 HN is a different, higher-nitrogen product again.
- What does Formula 8’s 12.5-25-25 mean?
- Low nitrogen, high phosphate and potash — a ripening / firm-growth soluble, not the balanced 20-20-20 of Miracle-Gro-style feeds.
More lawn & garden guides
Lawn guide
Weedkillers decoded: glyphosate vs triclopyr — paths, brambles and lawn
Lawn guide
Garden tonics decoded: seaweed, chelated iron, Epsom and rooting powder
Lawn guide
Lawn moss vs a nitrogen green-up — ferrous sulphate is not sulphate of ammonia
Lawn guide
Garden pests and disease: fungicides vs insecticides — not weedkillers
Related teardowns
Live stacks this guide points at — mix maths and DIY affiliate links on each page.
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.
Lawn & garden
Q4 All Purpose Plant Food
Vitax
- Retail pack
- £10.992.5 kg box
- Raw active
- Vitax Q4 5.3-7.5-10 + 3% MgO (20 kg professional sack)66455-26-3
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.
Lawn & garden
Formula 8 Low Nitrogen Feed
Chempak
- Retail pack
- £8.99750 grams
- Raw active
- Soluble fertiliser 12.5-25-25 (or near PK bloom 10-30-20)66455-26-3
This is not Miracle-Gro 20-20-20 and it is not Tomorite 4-3-8. Formula 8 is a low-N, high-P/K soluble at 12.5-25-25 for ripening onions, leeks, heathers and conifers. The same analysis sells as hydroponic bloom / PK-heavy soluble powder by the kilogram — some shops now label the range Incredigrow.
Lawn & garden
Miracle-Gro All Purpose Liquid Plant Food
Miracle-Gro
- Retail pack
- £6.001 litre
- Raw active
- Soluble NPK 20-20-20 (hydroponic grade)66455-26-3
A dilute bottle of soluble NPK. Hydroponic 20-20-20 (or similar) powder is the same three numbers, un-dyed and un-marketed, at a gram per litre instead of a capful of coloured water.
Lawn & garden
Tomorite Concentrated Tomato Food
Levington
- Retail pack
- £5.501 litre
- Raw active
- Soluble tomato fertiliser 4-4-8 (or 6-5-12)66455-26-3
A dilute high-potash bottle with a pinch of kelp. Soluble tomato feed around 4-4-8 (or 6-5-12) at 2 g/L is the same three numbers without the green dye. This is not Miracle-Gro 20-20-20 — tomatoes want potassium.
Lawn & garden
Nitrate of Potash
Westland
- Retail pack
- £5.991.5 kg box
- Raw active
- Potassium nitrate 13-0-46 (nitrate of potash)7757-79-1
This is not Tomorite (a dilute 4-3-8 bottle) and it is not 20-20-20. Potassium nitrate is 13-0-46: nitrogen plus potash in one salt. The garden-centre 1.5 kg box is agricultural KNO3 with a tomato on the front. Buy it in 5 kg.
Lawn & garden
Sulphate of Potash
Westland
- Retail pack
- £5.991.5 kg box
- Raw active
- Agricultural potassium sulphate (sulphate of potash, 0-0-48)7778-80-5
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.
Lawn & garden
Original Liquid Plant Food
Baby Bio
- Retail pack
- £2.75175 millilitres
- Raw active
- Soluble NPK 20-20-20 (hydroponic grade)66455-26-3
Baby Bio is a capful of soluble 6-6-6 in coloured water. Hydroponic 20-20-20 powder at a lower gram-per-litre rate is the same three nutrients without the tiny bottle markup.
Lawn & garden
Epsom Salts
Westland
- Retail pack
- £6.501.5 kg box
- Raw active
- Magnesium sulphate heptahydrate (Epsom salts)10034-99-8
The garden-centre box is agricultural Epsom salts with a picture of a tomato. MgSO4·7H2O is a commodity desiccant and bath salt. Buy it by the 5 kg bag, not 1.5 kg at a time. This is not BetterYou magnesium oil (that is chloride).
Lawn & garden
Sulphate of Ammonia
Westland
- Retail pack
- £7.501.5 kg box
- Raw active
- Agricultural ammonium sulphate 21% N7783-20-2
21% nitrogen as ammonium sulphate. The cardboard box is a portioned sack of a fertiliser merchants sell in 25 kg lots. It greens grass. It also acidifies — do not pile it on chalk-hating stone paths.
Lawn & garden
Fish, Blood & Bone
Westland
- Retail pack
- £5.491.5 kg box
- Raw active
- Fish, blood and bone meal (25 kg; typically 5-5-6 or 3-9-3)N/A - Organic Blend
This is not Growmore 7-7-7. It is an organic P-forward meal. Westland’s garden powder is 3-9-3 and, on the SDS, roughly half silica dust. A 25 kg sack of fish, blood and bone is the same job without the 1.5 kg box tax — check the analysis; trade bags are often 5-5-6.
Lawn & garden
Bone Meal
Westland
- Retail pack
- £5.491.5 kg box
- Raw active
- Steamed bone meal (agricultural, ~3.5-18-0)68476-17-1
Westland’s 1.5 kg box is steamed bone meal — slow organic phosphate (typically about 3.5-18-0), not Growmore 7-7-7, not superphosphate 0-17-0, and not Fish, Blood & Bone (a three-meal blend). A 25 kg agricultural sack is the same ground bone. CAS 68476-17-1 is the meal, not a secret rooting hormone.
Lawn & garden
Superphosphate
Westland
- Retail pack
- £6.991.5 kg box
- Raw active
- Triple superphosphate 46% P2O5 (or 17% as labelled granules)7758-87-4
A phosphorus-forward 0-17-0 — not Growmore 7-7-7, not fish blood and bone meal. Superphosphate is triple superphosphate granules sold in a small box. Merchants sell the same 17% P2O5 sack by the 25 kg for root establishment and autumn planting.
Lawn & garden
Garden Lime
Westland
- Retail pack
- £8.004 kg
- Raw active
- Agricultural ground limestone (calcium carbonate / dolomite lime)1317-65-3
Westland’s 4 kg box is agricultural lime: limestone calcium carbonate (CAS 1317-65-3) with dolomite (CAS 16389-88-1) — not hydrated lime, not ferrous sulphate, and not a weedkiller. A 25 kg ag-lime sack is the same pH-up salt. Test the soil first; keep it off rhododendrons.
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.