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Best bonsai fertiliser UK: what to check before you buy

Updated: October 2026

You are on amazon.co.uk with a 100 ml bottle at £3.35, a 900 g bag at £34.99, and a spray that sits in the bonsai fertiliser rank. The sticker and the bottle height do not tell you the dose, the nutrient line, or whether the product even goes in the soil. A best bonsai fertiliser UK search will not settle that for you. This page is the checklist. The [bonsai fertiliser comparison](/hub/fertiliser-soil-and-bark-mulch/bonsai-fertiliser) holds the seven listings side by side. If you buy through our links, we may earn a commission at no extra cost to you.

You are on amazon.co.uk with a 100 ml bottle at £3.35, a 900 g bag at £34.99, and a spray that sits in the bonsai fertiliser rank.

Our top picks

Biogold BioGold 900 g

Best overall

Biogold BioGold 900 g
7.6/10about £34.99
View offer
Growth Technology Ltd Bonsai Focus 100 ml

Rank 2

Growth Technology Ltd Bonsai Focus 100 ml
8.4/10about £3.35
View offer
Chrysal Liquid Bonsai Feed 250 ml

Preis-Tipp

Chrysal Liquid Bonsai Feed 250 ml
8.1/10about £9.95
View offer
On this page
  1. 1.What you are actually buying
  2. 2.The six checks, in order
  3. 3.How the prices in this set behave
  4. 4.Claims that are not evidence

What you are actually buying

Three forms sit in this set, and they are not interchangeable. A liquid concentrate is something you dilute and pour onto moist compost on a calendar. A slow-release pellet or cake sits on the soil and breaks down when you water. A mist is a spray for the leaves and the air around them. The UKGROW bonsai mist, 100 ml at £5.99, has no NPK and no dilution for the soil. That is a form problem, not a bargain. If you only looked at pack height, 100 ml of spray and 100 ml of Bonsai Focus look similar. According to the product data, Focus is mixed at 5 ml in 1 litre. The mist tells you nothing you can measure into a watering can.

The six checks, in order

Start with a dose you can follow. Millilitres per litre, or a stated way to place pellets, is the first line. A scraped mixing field that clashes with the bullets is not a dose. Bonsai Focus, 100 ml, prints 5 ml in 1 litre, and the listing also shows the ratio 1:200. The 250 ml liquid prints 4-6-6 and says the measurements are in the cap. A scraped field on that same listing says 1:1, while in the Amazon reviews one person describes 5 ml in a litre. Those two figures are not the same job. Do not treat 1:1 as the instruction. A missing NPK is a gap, not a zero. Only the 250 ml liquid prints 4-6-6. The format fork is on liquid vs pellet bonsai fertiliser.
Biogold BioGold 900 g

Testsieger

Biogold BioGold 900 g
7.6/10about £34.99
View offer

How the prices in this set behave

The cheap shelf is under £8. Focus is £3.35, the mist is £5.99, and Naruko pellets are £6.99 for 250 g. The 250 ml liquid at £9.95 is the bottle in the mid band that prints an NPK and has a review count in the hundreds. BioGold 900 g is £34.99, with no cakes-per-pot figure. According to the product data, Focus is 5 ml per litre, so 100 ml makes about 20 litres of mix. That does not mean the tree will drink 20 litres. How that looks week by week is on how to fertilise a bonsai. A missing NPK blocks a strength comparison. It does not, by itself, make the bottle illegal.

Claims that are not evidence

Organic on Naruko’s bullets is a seller line. The listing does not name a UK organic certifier. A line calling the 250 ml feed probably the best general purpose bonsai feed in the world is a slogan on the listing, not a test. The star row on the 1 litre bottle is 5.0 from one review. Focus is 4.5 from 978 reviews and still has no NPK. A perfect score from one person is a thinner buying signal than a 4.5 from a file you can actually read. Keep the listing whose printed instruction you will follow.

Common questions

Is a special bonsai bottle required, or is a balanced feed enough?
Kew says a fertiliser near 5:5:5 is enough, and that you do not need an expensive tailored bottle for that reason alone. You still need a dose you can measure and a pack that suits the number of trees. A listing with no NPK at all does not let you check the near 5:5:5 part. The bonsai-labelled bottle is useful when it prints the ratio and the millilitres, not because the word bonsai is on the cap.
Why is a 100 ml bottle £3.35 while a 900 g bag is £34.99?
They are different jobs. Focus at £3.35 is a concentrate: 5 ml in 1 litre, so 100 ml makes about 20 litres of mix. BioGold at £34.99 is 900 g of pieces you leave on the soil, with no count per pot in the bullets. For one small tree the bottle is the smaller commitment. For a collection that you will not mix for, the bag can be the one you actually use.
What does 4-6-6 mean, and what if the listing has no NPK?
The three numbers are the declared share of nitrogen, phosphorus and potassium, in that order. On the 250 ml liquid the bullets say 4-6-6, so nitrogen is the smaller figure and the other two are a little higher. Focus, the 500 g BioGold, the 1 litre UK GROW bottle, and the mist do not print an NPK in the fields on the listing. You cannot line their strength up against 4-6-6 or against Kew’s 5:5:5 tip.
Is organic on Naruko a certificate?
No certifier is named on that listing. The bullets say organic, slow release, and less likely to roll off. Organic there is the seller’s word. It does not tell you the pellets will stay clean, and the review sample keeps returning to mould within a day or two. Read them as a pattern, not as proof the bag is fake or proof it is working.
Should I trust 5.0 from one review more than 4.5 from 978?
No. UK GROW’s 1 litre feed is 5.0 from one amazon.co.uk review, at £11.99, with no NPK and a dose written as a few drops. Focus is 4.5 from 978 reviews, at £3.35, with 5 ml per litre printed. The single five-star line can be a real person’s tree. It is not a larger sample. Stars do not repair a missing ratio.

Related pages

Best bonsai feed

Bonsai fertiliser

How to fertilise a bonsai without drowning the pot

Indoor bonsai fertiliser for a ficus that stays indoors

Liquid vs pellet bonsai fertiliser, mould and smell

Sources

Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the seven amazon.co.uk listings captured on 19 October 2026. Scores are editorial, not a laboratory test. A missing NPK is a gap, not a zero. The scraped 1:1 field is not the dose for the 250 ml liquid.

  1. RHS, bonsai (retrieved 19 October 2026)
  2. RHS, feeding plants (retrieved 19 October 2026)
  3. Federation of British Bonsai Societies, cultivation (retrieved 19 October 2026)
  4. Federation of British Bonsai Societies, the bonsai year (retrieved 19 October 2026)
  5. Kew, top ten bonsai tips (retrieved 19 October 2026)
  6. Growth Technology, safety data sheets (retrieved 19 October 2026)
  7. Growth Technology, indoor bonsai leaflet (retrieved 19 October 2026)
  8. legislation.gov.uk, retained Regulation (EC) No 2003/2003 Article 9 (retrieved 19 October 2026)
  9. legislation.gov.uk, Fertiliser Regulations 2006 (retrieved 19 October 2026)
  10. ASA ruling, The SEER Centre Trust (retrieved 19 October 2026)