The best bonsai composts, compared.
Top pick: UK GROW Bonsai Focus 20 litre bucket Best value: UK GROW bonsai potting mix 30 litres – Lowest credible price per litre when you will use the sack, about £0.63, at about £18.99. Updated October 2026.
Bonsai compost on amazon.co.uk is a potting medium for a shallow pot, not a fertiliser and not the heap at the bottom of the garden. You are choosing a bark and grit bag, a shared cactus-and-bonsai compost, or akadama, which these listings do not contain. Quality here means an open mix that holds some water and lets the rest drain, matched to the species and to how often you can water. The RHS says to repot in spring, keep the compost just moist, and feed lightly in the growing season. A star row does not prove one bag suits a pine, an azalea and a ficus at once. What to check before you pay is in the [bonsai compost buying guide](/hub/fertiliser-soil-and-bark-mulch/bonsai-compost/sub/bonsai-compost-buying-guide). Bonsai4me’s test is enough water between waterings, excess gone at once, and particles that leave air gaps. Says multipurpose compost can be too wet in a bonsai pot and can lead to root rot. Cheshire Bonsai Society describes 2:1:1 akadama, lava and pumice for older maples and 1:1:1 for conifers, and says you must feed because the granules are inorganic. Lime-haters need an ericaceous mix, not lime-containing John Innes.
Bonsai compost on amazon.co.uk is a potting medium for a shallow pot, not a fertiliser and not the heap at the bottom of the garden.
38 products checked · 62 hrs invested · +21,400 readers
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Personal buying guide
Question 1 of 2
How many trees are you potting?
The 20 litre Focus bucket is £21.99, listed at 8 kg, with a listing line of 5.0 from 2 reviews and no review text in the saved listing. Two five-star clicks are not a reason to treat this as the best mix in the set. The title names composted bark, grit and fine sand, and it does not name peat. Indoor use is asked and not answered. At about £1.10 a litre it costs more than the 20 litre Focus that is not sold as a bucket, and those two reviewers did not describe what arrived. The unit count field says 1.0 gram. A lid is useful if you will keep it on, and it is a weak reason to pay £21.99 when the comments are missing.
Pros
Cons
Best for: You want a large tub of the named Focus recipe and you will judge the contents yourself.
Less suitable: You are choosing from star ratings, or you only have one small tree.
Specifications
Common questions
What did the two reviewers write?
Not stated. The listing line is 5.0 from 2. The saved listing has no review text.
What does the title say is in the bucket?
Composted bark, grit and fine sand.
Is indoor use stated?
Not stated. The listing asks and the bullets do not answer.
The UK GROW Bonsai Focus 3 litre listing is the only title in this set that says a selection of peats, plus composted bark, grit and fine sand. It is £7.99, listed at 1.16 kg, with 4.7 from 12 reviews. The saved listing contains one review text, the word Perfect, so the star row is larger than the comments you can read. This title does not say bucket. The unit count field says 1.0 gram, which conflicts with a 3 litre title, though the volume field does say 3 litres. If you want to avoid peat, this is the Focus row to leave. If you accept peat on the label, £7.99 buys a stated 3 litres at the same shelf price as the 1 litre bags.
Pros
Cons
Best for: You want about 3 litres of a named Focus mix and you have read the peat line.
Less suitable: You want peat-free compost, a bucket, or a review file you can actually read.
Specifications
Common questions
Does this listing include peat?
The title says a selection of peats, plus composted bark, grit and fine sand.
Is it a bucket?
Not stated. This title does not say bucket. Separate Focus ASINs are titled as buckets.
What do the reviews say?
The listing shows 4.7 from 12 reviews. The saved listing contains one review text: Perfect.
This Focus listing is titled as a 3 litre bucket of composted bark, grit and fine sand, at £9.99 and 1.16 kg, with 4.7 from 10 reviews. The only review text says it came in a bag, not a bucket, and had pellets the buyer was unsure about. A bucket that arrives as a bag is a description problem under the Consumer Rights Act 2015, not proof that a later dead tree was caused by the mix. Peat is not named, and the words selection of are unfinished on the title. The unit count again says 1.0 gram. Indoor use is asked and not answered. You pay £2 more than the 3 litre Focus title that names peats, for a bucket the one written review did not receive.
Pros
Cons
Best for: You want a small named bark and grit mix and you will check that a bucket actually arrives.
Less suitable: You need a peat-free promise, or you are buying mainly for the tub the review did not get.
Specifications
Common questions
Did the review receive a bucket?
No. The only review text says it came in a bag, not a bucket, and had pellets the buyer was unsure about.
Is peat named?
Not stated. The title says composted bark, grit and fine sand. The words selection of are unfinished.
Can it be used indoors?
Not stated. The listing asks and does not answer.
The Invigortex 1 litre bag is the small pack when you are filling one shallow bonsai pot and the title has to say indoor and outdoor. On amazon.co.uk it is £7.99, listed at 800 g, with 4.6 from 38 reviews. That star row is shared with the other Invigortex size, so it is not a verdict on this litre alone. The listing says fast-draining and names juniper, ficus, maple, pine and more, but the saved listing does not name akadama, bark or grit. One shared review says it is not suitable for redwood. At about £8 a litre it is a dear way to buy volume, which is what you pay to finish the bag on a single small tree, and the title and the volume field both say 1 litre.
Pros
Cons
Best for: You are repotting one small indoor or outdoor bonsai and you can accept unnamed ingredients.
Less suitable: You need a named bark and grit recipe, a pine-only mix, or litres for several trees.
Specifications
Common questions
Does the listing say this 1 litre mix is for indoor bonsai?
Yes. The title says it is ideal for indoor and outdoor bonsai, in bonsai pots, containers and training trays.
Which trees does the listing name?
The bullets name juniper, ficus, maple, pine, and more. One shared review says it is not suitable for redwood.
Are akadama, bark or grit named?
Not stated. The listing does not name those ingredients.
This Invigortex listing prints 3 litre on the title and costs £10.95, with an item weight of 1.6 kg. The volume field says 1 litre and the unit count is 1,000 ml, and those figures are not reconciled, so a price per litre would be a guess. The same 4.6 from 38 reviews sits on the 1 litre saved listing, which means you should treat the pool as shared. The bullets still say fast-draining and indoor and outdoor, and they still do not name akadama, bark or grit. One shared review rules out redwood. Open this only if the parcel matches the 3 litre title, because the catalogue conflict is something you cannot settle from the page alone.
Pros
Cons
Best for: You have already checked that the parcel is the 3 litre pack the title describes.
Less suitable: You need a litre figure you can trust before you pay, or a mix with named ingredients.
Specifications
Common questions
Is this pack 3 litres?
The title says 3 litre. The volume field says 1 litre and the unit count is 1,000 ml. Those figures are not reconciled.
Does the listing name the ingredients?
Not stated. It says naturally sourced and hand-mixed. Akadama, bark and grit are not named.
Do the 38 reviews belong only to this size?
The same review texts are on the 1 litre Invigortex saved listing. Treat 4.6 from 38 as a shared parent pool.
The Miracle-Gro 6 litre pack is the bag to open when the same shelf holds cacti and succulents as well as one bonsai, and it is a poor choice when you are mixing for a pine. It is £9.79, listed at 4.07 kg, with 4.5 from 2,231 reviews, the largest file in the set. Most of the sampled reviews are about cacti, aloe and succulents, and a few mention bonsai. Repeated complaints are a wet bag, lumps or pieces of wood, and water held too long. The product title says Miracle-Gro and the brand-name field says VTANMS. The Amazon bullets do not name ingredients, do not say peat-free, and do not say indoor. At about £1.63 a litre the shelf price is modest, and the review count still does not show that the mix drains in a shallow bonsai pot.
Pros
Cons
Best for: You keep cacti or succulents beside one indoor bonsai and you will watch how fast the pot dries.
Less suitable: You want a named bark and grit bonsai mix, or a pine, maple or azalea with its own recipe.
Specifications
Common questions
Does the Amazon listing say it is peat-free?
Not stated. The bullets do not say peat-free or name ingredients.
Who is the brand?
The product title says Miracle-Gro. The brand-name field says VTANMS.
What do reviewers mention most?
Most of the sampled reviews are about cacti, aloe and succulents. Repeated complaints are a wet bag, lumps or wood pieces, and water held too long. A few reviews also mention bonsai.
The Topline listing is a bundle, not compost on its own: 10 litres of peat-free compost for cacti, bonsai and succulents, 175 ml of concentrated cactus feed, and a card, at £13.99 and 5.6 kg, with 4.5 from 62 reviews. The title says indoor plants and peat-free, which is the clearest peat wording in this set. The description also mentions Miracle-Gro potting compost while the brand field says Topline, so the parcel has to match what you meant to buy. One buyer says the soil holds water, turns to sludge and compacts, including after they mixed in perlite. Other reviews say a cactus was happy. The 10,000:175 figure is a catalogue ratio, not a feeding dose you can follow without the bottle label. The £13.99 pays for feed as well as compost, which helps only if you wanted both.
Pros
Cons
Best for: You want a peat-free cactus and bonsai compost and a small bottle of cactus feed together.
Less suitable: You only wanted compost, or the last bag of this mix stayed wet for hours in the pot.
Specifications
Common questions
Is this only compost?
No. The title is a bundle: 10 litres of peat-free compost, 175 ml of concentrated cactus feed, and a Topline card.
Does the listing say peat-free?
Yes. The title says peat free.
What is the main complaint in the reviews?
One buyer says the soil holds water, turns to sludge and compacts, including after they mixed in perlite. Other reviews say their cactus was happy.
The UK GROW Bonsai Focus 5 litre bucket is the top pick in this set when you want a named bark, grit and sand mix and a review file you can actually read. On amazon.co.uk it is £10.99, listed at 2.05 kg, with 4.4 from 41 reviews, the largest Focus file here. Reviewers praise the resealable tub. One buyer’s second tub smelled mouldy, felt like coffee grounds, and had small insects they thought were springtails. Another order arrived as about 2 kg in a bag instead of a bucket. The title does not say peat, and the bullets say balanced pH without giving a number. At about £2.20 a litre it costs more per litre than the 20 and 30 litre bags, which is what you pay for a tub you can close between a few trees.
Pros
Cons
Best for: You have a few bonsai pots and you want a tub of named bark, grit and sand you can close.
Less suitable: You need the cheapest litres, a peat-free certificate, or a mix for a pine that must stay very dry.
Specifications
Common questions
What is in the mix, according to the title?
Composted bark, grit and fine sand. This title does not say peat.
What went wrong in reviews?
One buyer’s second tub smelled mouldy, felt like coffee grounds, and had small insects they thought were springtails. Another order arrived as about 2 kg in a bag instead of a 5 kg bucket.
Is the pH stated as a number?
Not stated. The bullets say balanced pH. One reviewer says the label is pH neutral.
The UK GROW 30 litre bag is the best value in this set when you have several pots and you will use the sack before it sits open. It is £18.99, listed at 12 kg, with the same 4.4 from 6 reviews as the 1 litre bag. On the title volume that is about 63p a litre, the lowest price per litre here. The bullets list bags up to 20 litres while this title says 30 litres, so the sack you receive still has to match the title. Ingredients are not named. The shared reviews mention a Japanese maple doing well and a description one buyer called misleading. A 12 kg bag is awkward in a small flat, and an open sack is how compost picks up fungus gnats.
Pros
Cons
Best for: You have several bonsai pots and you will close or use a 12 kg sack.
Less suitable: You have one windowsill tree, or you need a named ingredient list before you buy.
Specifications
Common questions
Does the listing name the ingredients?
No. One shared review says the description is misleading and to read technical details. The raw technical block has no ingredient line.
Is indoor use stated?
Not stated. The bullets do not say indoor or outdoor.
How heavy is the 30 litre bag?
The listing says 12 kg.
The UK GROW 1 litre bag is £7.99, listed at 400 g, with 4.4 from 6 reviews shared with the 30 litre bag. The bullets say organic and inorganic materials for conifers, deciduous and flowering bonsai, and they do not name those materials. Indoor use is asked on the listing and not answered. Three review texts are written out: fine for bonsai, a Japanese maple thriving, and one note that the description is misleading and that you should read the ingredients. There is no ingredient table in the saved listing. At about £8 a litre it matches the other 1 litre shelf price, and you still do not know what is in the bag.
Pros
Cons
Best for: You want a 1 litre trial of the UK GROW potting mix and you will read the bag label when it arrives.
Less suitable: You need named grit and bark, an indoor claim, or a review file larger than six shared stars.
Specifications
Common questions
Can it be used for indoor bonsai?
Not stated. The listing asks the question and the bullets do not answer it.
Is it made from organic materials?
The bullets say a mix of organic and inorganic materials. They do not say it is wholly organic, and they do not name the ingredients.
What did reviewers say?
Three shared reviews: fine for bonsai, a Japanese maple thriving, and one note that the description is misleading and to read the ingredients. No ingredient table is in the saved listing.
The 20 litre Focus mix is £17.99, listed at 8 kg, and the saved listing has no customer-review line and no review text. The title names composted bark, grit and fine sand, and it does not say bucket. The 20 litre bucket is a different listing. On the title volume that is about 90p a litre, cheaper per litre than the 5 litre tub, and you have no written reviews in this file to compare the texture with the smaller Focus packs. The unit count field says 1.0 gram, which does not match 20 litres. Peat is not named. Buy the litres only if you can return a pack that is not as described.
Pros
Cons
Best for: You need about 20 litres of the named Focus recipe and you can inspect the bag on arrival.
Less suitable: You want reviews you can read, or a bucket with a lid.
Specifications
Common questions
What is the star rating?
Not stated. The saved listing has no customer-review line and no review text.
Is this the 20 litre bucket?
No. This title does not say bucket. The 20 litre bucket is a different ASIN.
Does the title name peat?
Not stated. It names composted bark, grit and fine sand. The words selection of are unfinished.
Eleven amazon.co.uk listings were scored from the stored pages and the review notes already on file. There is no laboratory test. Fast-draining, superior drainage, balanced pH, all types, indoor and outdoor, and peat-free are the seller’s claim unless a review contradicts them. A price per litre uses the title volume only when the volume field agrees. The weights below sum to 100.
Amazon evidence
30%Star rating on amazon.co.uk, then the size of that listing’s review file, with a deduction when the same texts are shared with another size or when almost no review is written out. Miracle-Gro at 4.5 from 2,231 takes the most of this block. A 5.0 from 2 with no text, and a 20 litre row with no review line, take almost none.
Listing honesty
25%Named ingredients, a litre figure that matches the volume field, and peat words you can see. The 5 litre Focus bucket names composted bark, grit and fine sand. The Invigortex title that says 3 litres while the volume field says 1 litre loses most of this block. A 1.0 gram unit count on the Focus rows is a deduction.
Review outcome
25%Comments that match a shallow bonsai pot score higher when the sample is large enough to read. A resealable Focus tub scores. A mouldy second tub, a bag sent instead of a bucket, a wet Miracle-Gro bag, and a Topline bag that turned to sludge are deductions. Two unread five-star clicks do not fill this block.
Value
20%Stored GBP price against a litre figure the listing can support. UK GROW 30 litres at about £18.99 is about £0.63 a litre and takes this block. The 1 litre bags at £7.99 are about £8 a litre. The conflicting Invigortex title is not given a price per litre.
Match the mix to the pot and the species before you match the star line. Prices below are the stored amazon.co.uk figures for these eleven listings. This is not a laboratory test.
Bonsai compost is the mix you put in a shallow bonsai pot. It is not a fertiliser, and it is not the heap at the bottom of the garden. On amazon.co.uk the bags in this set are a bark, grit and sand style mix, a shared cactus-and-bonsai compost, or a potting mix that does not name its ingredients. Akadama, pumice and lava are not in these eleven listings. Drainage and air come first. Bonsai4me’s test is enough water between waterings, excess gone at once, and particles that leave air gaps.
BBC Gardeners’ World says multipurpose compost can be too wet in a bonsai pot and can lead to root rot. It is acceptable for sowing seed. An open mix that drains is the point of a bonsai compost.
Suitable for all bonsai is a claim, not a trial. Maples want more moisture than pines. Keep some old soil on pines. Lime-haters need an ericaceous mix, not lime-containing John Innes.
A 12 kg sack is awkward in a small flat, and an open sack is how compost picks up fungus gnats. A bucket only helps if the tub you ordered is the tub that arrives, and if you keep the lid on.
Bonsai4me’s test is the practical one: enough water between waterings, excess gone at once, and particles that leave air gaps. BBC Gardeners’ World says multipurpose compost can be too wet in a bonsai pot and can lead to root rot. It is acceptable for sowing seed. That is why a bark, grit and sand mix is a different product from a general potting compost. Species changes the mix. Maples want more moisture than pines.
Focus titles name composted bark, grit and fine sand. One 3 litre title also says a selection of peats. Invigortex does not name akadama, bark or grit. The UK GROW potting-mix bags say organic and inorganic materials and do not name them. Miracle-Gro’s amazon bullets do not name ingredients, and the brand field says VTANMS. Topline says peat-free and is a 10 litre compost plus 175 ml of cactus feed, not compost alone. About 1–3 litres fills one small tree.
Three typical situations, each with a recommendation from this comparison.
A first ficus or Chinese elm needs a small, open mix and a gentle spring repot, not a 30 litre sack. The Invigortex 1 litre bag is about £7.99, listed at 800 g, and the title says indoor and outdoor. Ingredients are not named, and the 4.6 from 38 reviews is shared with the other Invigortex size.
Several outdoor trees need volume and a mix you can close, with a drier recipe for pines than for maples. The UK GROW Bonsai Focus 5 litre bucket is the top pick at about £10.99, with bark, grit and sand named and 4.4 from 41 reviews. One second tub smelled mouldy. About £2.20 a litre is the price of a tub you can close.
A cactus-and-bonsai household can share one sandier compost if you accept it is not an akadama mix and you watch for water sitting in the pot. The Miracle-Gro 6 litre pack is about £9.79, with 4.5 from 2,231 reviews, mostly about cacti and succulents. Wet bags and water held too long come up repeatedly.
The top pick in this set is the UK GROW Bonsai Focus 5 litre bucket at about £10.99. The title names composted bark, grit and fine sand, amazon.co.uk shows 4.4 from 41 reviews, and reviewers praise a resealable tub. One second tub smelled mouldy, and another order arrived short in a bag. The best value is the UK GROW 30 litre bag at about £18.99, about £0.63 a litre on the 30 litre volume field, with a thin shared review file and unnamed ingredients. None of these listings contains akadama. None of these scores is a laboratory test.
UK GROW bonsai potting mix 30 litres
Lowest credible price per litre when you will use the sack, about £0.63, at about £18.99.
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 sources from the research digest, used for this page in October 2026. Prices, stars and review counts are the figures stored from the eleven amazon.co.uk listings in this set. A drainage line, an all-types line and a peat-free line are listing claims. This is not a laboratory test. Selling peat compost was not shown to be an England-wide offence on 19 October 2026.
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.
