The best bonsai fertilisers, compared.
Top pick: UK GROW bonsai feed 1 litre Best value: Liquid Bonsai Feed 250 ml – Next listing that prints an NPK, 4-6-6, and has at least 200 reviews, at about £9.95 with 4.4 from 885 reviews. Updated October 2026.
A bonsai fertiliser on amazon.co.uk is a liquid you dilute, a pellet or cake on the soil, or a spray in the bonsai fertiliser rank, for a tree in a very small pot. You usually keep one indoor gift tree or a small outdoor collection, and you need a printed dose, a season, and a pack that matches the number of trees. The Royal Horticultural Society and the of British Bonsai both describe little and often in the growing season, on moist compost, plus a wait after repotting. Do not treat a scraped 1:1 field as the dose. Liquid versus pellets is in the [bonsai fertiliser liquid versus pellets](/hub/fertiliser-soil-and-bark-mulch/bonsai-fertiliser/sub/bonsai-fertiliser-liquid-vs-pellets) guide. The tree sits in a very small pot, so the compost holds little nutrient. A star line is not a growth trial.
A bonsai fertiliser on amazon.co.uk is a liquid you dilute, a pellet or cake on the soil, or a spray in the bonsai fertiliser rank, for a tree in a very small pot.
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Personal buying guide
Question 1 of 2
How will you feed the tree?
UK GROW’s 1 litre bonsai feed is £11.99 and 5.0 from one amazon.co.uk review. The bullets say a few drops in water, all varieties from juniper to ficus, stronger roots, a longer life, and a natural defence against disease and pests. None of those lines is backed by an NPK or a trial in the saved listing. The rank shown is in hydroponic nutrients, not in bonsai fertilisers. The single review describes new growth on a large collection after mixing with water. Indoor use and organic status are asked and not answered. A 90-day warranty line is on the listing.
Pros
Cons
Best for: You want a large bottle of liquid and you will not rely on a printed NPK.
Less suitable: You want a dose in millilitres and a review count you can weigh.
Specifications
Common questions
How much do you dilute?
The listing says a few drops mixed with water. It does not give millilitres per litre.
Does the listing name an NPK?
The listing does not name an NPK.
What do the reviews say?
There is one UK review. It reports new growth after the first use on a large personal collection, and says mixing with water was easy.
BioGold 900 g is £34.99 and 4.6 from 96 amazon.co.uk reviews, the highest star line in this set. You leave the pieces on the soil. The bullets say it is safe for all trees, resists mould and insects, and is shaped not to roll. There is no cakes-per-pot figure. The model field says NPK - 5.5 and a scraped field says 5:5:5. Of 32 UK reviews, people praise not mixing and bags that last, including through rain. One reviewer dislikes a cat-litter smell when the bag is opened, and another says the pieces look large on a small tree.
Pros
Cons
Best for: You have several trees and you would rather leave cakes on the soil than mix a bottle.
Less suitable: You have one small indoor tree and you want a printed millilitre dose.
Specifications
Common questions
How many pieces does the listing say to use?
The bullets do not give a count per pot. They describe controlled feeding and a shape that should not roll off.
Does the listing claim it resists mould?
Yes. The bullets say it resists moulding and insects. The 32 UK reviews in the saved listing do not describe mould on this bag.
What NPK is printed?
The model field says NPK - 5.5. A scraped field says 5:5:5. The file does not reconcile them.
Growth Technology Bonsai Focus is a 100 ml liquid at £3.35, listed at 4.5 from 978 amazon.co.uk reviews. The listing tells you to mix 5 ml in 1 litre, and to use it from March until August with occasional winter feeds. It names humic and fulvic acids and seaweed, and it does not print an NPK. Of 50 UK reviews read, many describe greener growth, and a repeated complaint is that the bottle looks too small until you dilute it. One reviewer worked the 100 ml out to about 20 litres of mix. The listing asks about indoor use and about organic status and does not answer either.
Pros
Cons
Best for: You have one or two trees and you will measure 5 ml into a litre.
Less suitable: You want a printed NPK, or you will judge the bottle by its height and then feel short-changed.
Specifications
Common questions
How much Bonsai Focus does the listing say to mix?
Mix 5 ml in 1 litre of clean water. The listing also gives the ratio 1:200.
Does the listing say it is organic?
The page asks whether it is organic and does not answer that in the bullets.
Can it be used on indoor plants?
The bullets do not answer indoor use. Reviewers in the saved listing mention ficus.
This 250 ml liquid is £9.95 and 4.4 from 885 amazon.co.uk reviews. The brand field says Chrysal and the manufacturer field says Got-Bonsai. The bullets call it a 4-6-6 feed with measurements in the cap, and they also call it probably the best general-purpose bonsai feed in the world, which is a slogan rather than a test. The scraped mixing field says 1:1, while one reviewer dilutes 5 ml in a litre once a week. Of 50 UK reviews read, greener leaves and a long-lasting bottle are the common praise. A few trees were already failing, and one cap arrived broken.
Pros
Cons
Best for: You want a liquid that prints 4-6-6 and a cap, and you will follow the bottle rather than the scraped 1:1 field.
Less suitable: You need a single unambiguous millilitre dose in the short bullets.
Specifications
Common questions
What NPK does the listing print?
The bullets and the model field say 4-6-6.
How do you measure a dose?
The listing says the measurements are inside the cap. One reviewer says the cap arrived broken. A scraped field says 1:1, and a reviewer describes 5 ml in 1 litre. Those two figures are not the same.
Does the listing say it is for indoor bonsai?
The page asks and does not answer. Reviewers describe indoor trees, including Chinese elm.
This BioGold listing is 500 g at £19.99, with 4.4 from 29 amazon.co.uk reviews. The title says BioGold and the saved listing has no brand field, no NPK, and no dose. The form is granules and powder. Ten UK reviews praise leaving the pieces in place instead of mixing a liquid. One reviewer, who wanted the branded bag in the photo, received an unmarked plastic bag. Indoor use and organic status are questions on the page with no answer. A reviewer’s couple of rocks for a month or two is that person’s habit, not a label instruction.
Pros
Cons
Best for: You want BioGold cakes and a 500 g bag is enough.
Less suitable: You need the nutrient line printed, or you need the retail bag shown in the photo.
Specifications
Common questions
What nutrients does the listing declare?
The page asks what nutrients it has and does not answer.
Is this the same pack as the 900 g BioGold?
No. This ASIN is 500 g at £19.99. The 900 g bag is B00HLS7V38 at £34.99.
Did the pack match the photo?
One reviewer says the photo showed an original bag and the delivery was a clear unmarked bag.
UKGROW Bonsai Mist is a 100 ml spray at £5.99, listed at 4.1 from 7 amazon.co.uk reviews and ranked 15 in Bonsai Fertilisers. The bullets mix hydration, nutrients, flowering, and pest resistance, and they do not print an NPK or a dose. The title is cut off at Formul. Indoor use and made in the UK are asked and not answered. Two UK reviews in the saved listing say little more than that the product is good, and neither describes a tree. Buy this only if you wanted a mist. It is not a measured concentrate.
Pros
Cons
Best for: You want a small spray and you already have a proper feed for the soil.
Less suitable: You need a diluted fertiliser with a printed dose.
Specifications
Common questions
Is this a soil fertiliser you dilute?
The listing sells it as a nourishment spray for hydration and growth. It does not give a soil dilution or an NPK.
Does the listing say it is made in the UK?
The page asks and does not answer.
What do the reviews say?
The saved listing has two UK reviews. Both are a few words and neither describes a result on a tree. The star line is 4.1 from 7 reviews.
Naruko 250 g loose pellets are £6.99 and 3.9 from 72 amazon.co.uk reviews. The title says Naruko, the brand field says WOOTONG, and the manufacturer field says Naruko. Bullets say slow release, easy to use, organic, and less likely to roll off. There is no dose. A scraped field says 5:5:5. Of 19 UK reviews in the file, mould within a day or two is the line that repeats, with smell and little visible effect next to it. A minority report new leaves, and one reviewer treats the mould as normal organic breakdown.
Pros
Cons
Best for: You want a cheap slow-release pellet and you accept surface mould as a possibility.
Less suitable: You want a clean soil surface, or a liquid you can measure.
Specifications
Common questions
Does the listing say the pellets are organic?
Yes. The bullets say organic. They do not name a certifier.
How much do you put on a pot?
There is no gram dose in the file. A scraped field says 5:5:5, which reads as NPK rather than a count of pellets.
What do the reviews say about mould?
Several UK reviews say the pellets go mouldy or mushy within a day or two. One reviewer says that mould is organic breakdown. Another says the bag is fish food, not bonsai food.
Seven amazon.co.uk listings were scored from the stored pages. Shelf prices, stars and review counts are the figures already in the product file. The award decision is 20 October 2026. There is no laboratory test. The score is an editorial 0–100 for how usable the listing is, not a growth trial. Stars are about (rating divided by 5) times 60. Review volume is up to 15 points: 15 at 500 reviews or more, 10 at 50–499, 5 at 20–49, and 0 under 20. The 1 litre listing also loses 10 because the count is a single review. Listing detail covers a printed dose, a printed NPK or a stated claim, and Naruko loses points for the mould theme in the UK reviews. The highest score is the top pick, once. Best value is the next listing that prints an NPK and has at least 200 reviews, because the top pick is also the lowest shelf price and the award field holds one value. The weights below sum to 100.
Amazon stars
60%About (amazon rating divided by 5) times 60, rounded. A 4.5 becomes 54. A 5.0 becomes 60. This is the star line on that amazon.co.uk listing, not a growth trial.
Review volume
15%500 reviews or more scores 15. From 50 to 499 scores 10. From 20 to 49 scores 5. Under 20 scores 0. The 1 litre listing also loses 10 because the count is a single review.
Listing detail
25%A printed dose, a printed NPK, or a stated claim, as already written in each score note. A scraped ratio that clashes with the bullets is not a dose. Naruko loses points for the mould theme in the UK reviews.
Buy the dose and the form before you buy the star line. A liquid, a pellet and a mist are not one job. Prices below are amazon.co.uk shelf prices on 19 October 2026. This is not a laboratory test.
A bonsai fertiliser on amazon.co.uk is a liquid you dilute, a pellet or cake on the soil, or a spray in the bonsai fertiliser rank. The tree sits in a very small pot, so the compost holds little nutrient. UK buyers usually keep one indoor gift tree or a small outdoor collection. What matters is a dose you can follow, a printed NPK when you need to compare strength, and a pack that matches the number of trees. A star line is not a growth trial.
At 5 ml per litre, 100 ml of Focus makes about 20 litres of mix. That is a label rule of thumb. Reviewers who dilute it say the bottle lasts. Reviewers who judge the bottle before they dilute it call it small or overpriced.
The Federation of British Bonsai Societies says wait at least six weeks after repotting. The Royal Horticultural Society allows a slow-release at repotting, then a low-dose liquid about every two weeks. Feeding in the week you repot is the mistake.
A small pot is a reason to stay at the label dose, not to raise it. Excess feed can damage bonsai, and overfeeding makes soft growth. Lack of water is the usual failure. Soak dry soil first, and do not treat leaf drop as hunger.
A dose you can follow is millilitres per litre, or a stated way to place pellets. A scraped mixing ratio that clashes with the bullets is not a dose. Focus prints 5 ml in 1 litre. The 250 ml liquid prints measurements in the cap and 4-6-6, but a scraped field says 1:1 and a reviewer uses 5 ml in a litre. Follow the bottle, not that scraped field. UK GROW says a few drops and gives no millilitres. BioGold and Naruko do not print a cakes-per-pot or gram dose.
Whether nitrogen, phosphorus and potassium are printed is how you compare strength. A missing NPK is a gap, not a zero. In this set only the 250 ml liquid prints 4-6-6 in the bullets. Focus names humic and fulvic acids and seaweed, and it does not print an NPK. BioGold 900 g has NPK - 5.5 in the model field and 5:5:5 in a scraped field. Do not treat those as one agreed analysis. Naruko has a scraped 5:5:5 and an organic line with no certifier. The 1 litre bottle and the mist print no NPK.
Three typical situations, each with a recommendation from this comparison.
Use a measured liquid, and pause around November to January if you follow the Growth Technology indoor leaflet. Bonsai Focus 100 ml is about £3.35, with 4.5 from 978 reviews, and the listing says 5 ml in 1 litre. It does not print an NPK. The bullets do not answer indoor use.
Leave cakes on the soil if weekly mixing will not happen. BioGold 900 g is about £34.99 and 4.6 from 96 reviews. There is no cakes-per-pot figure, the two NPK fields do not match, and the pieces can smell and look large on a small tree. Naruko is cheaper, and its reviews cluster on mould.
Only the 250 ml liquid prints 4-6-6 in the bullets. It is about £9.95, with 4.4 from 885 reviews and a measuring cap. A scraped field says 1:1, and a reviewer uses 5 ml in 1 litre. Follow the bottle. The other listings are a form and a dose, not a strength comparison.
The top pick is Bonsai Focus 100 ml at about £3.35. The listing prints 5 ml per 1 litre and amazon.co.uk shows 4.5 from 978 reviews. It does not print an NPK. The best value is Liquid Bonsai Feed 250 ml at about £9.95, the next listing that prints an NPK and has at least 200 reviews. Naruko is cheaper at about £6.99, and mould in the reviews plus 3.9 from 72 reviews keeps it off that badge. The £5.99 mist has no dose. A 5.0 from one review does not outrank 4.5 from 978. None of these scores is a laboratory test.
Liquid Bonsai Feed 250 ml
Next listing that prints an NPK, 4-6-6, and has at least 200 reviews, at about £9.95 with 4.4 from 885 reviews.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
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.
Expert source (DIY & tools): Lee Burkhill (Garden Ninja) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are from the listings. This is not a laboratory test.
