The best orchid soils, compared.
Top pick: UK GROW orchid bark and perlite 2 L bucket Best value: Miracle-Gro Peat Free Orchid 10 L – Lowest price per litre among bags that pass the same gate: about £0.60 a litre, about £6.00 for 10 litres, with peat free on the title. Updated October 2026.
Orchid soil in UK shops is pine bark, or bark mixed with perlite or fired clay granules. It is not garden soil and not multipurpose compost. You buy it when you repot a supermarket moth orchid or a small collection. The bag has to match the genus, the chip size, and how many litres the pot will take. Moth orchids and cymbidiums want coarse bark, about 8–15 mm. Finer chips, about 5–8 mm, suit other orchids. Slipper orchids need a different recipe, and vandas are grown without compost. A seller rule of thumb is about 1 litre for an 11 cm pot, about 5 litres for 14–20 cm, and about 10 litres for 20–28 cm. The Royal Horticultural Society says moth orchids need bark-based compost, never loam or multipurpose compost, and that you should refresh the bark about every two years once it holds too much water. Call a mix peat-free only when the pack prints those words. What to check, in order, is set out in the [orchid soil buying guide](/hub/fertiliser-soil-and-bark-mulch/orchid-soil/sub/orchid-soil-buying-guide).
Orchid soil in UK shops is pine bark, or bark mixed with perlite or fired clay granules. It is not garden soil and not multipurpose compost. You buy it when you repot a supermarket moth orchid or a small collection.
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Personal buying guide
Question 1 of 2
How many plants are you repotting?
The UK GROW 2 litre listing is graded pine bark and perlite in a reusable bucket at about £8.99, about £4.50 a litre, and the item weight is 800 g. The bullets name Cattleya, Phalaenopsis, Dendrobium, Oncidium, Vanda, Paphiopedilum and Brassia, and they claim a sterilised formula free from pathogens, which is seller text rather than a result measured here. The star line is 4.8 from 12 ratings, the highest stars in the set and a small sample. Only two UK review lines are on file, both a single sentence, saying the product is high quality and that it does the job, so there is no complaint theme to weigh against that score. The coverage field says Medium, and there is no millimetre grade and no peat-free line. Twelve ratings sit under the 50-rating line used for a badge, even before you look at price. At about £4.50 a litre you are paying for a small bucket, not for a cheaper compost.
Pros
Cons
Best for: You want a 2 litre bucket for one or two pots and you treat 12 ratings as a thin sample.
Less suitable: You want a badge-level review count, a peat-free statement, or a lower price per litre from a larger bag.
Specifications
Common questions
What comes in the pack?
The listing says one premium orchid bark and perlite mix in a 2 litre reusable bucket.
Which orchids does the listing name?
Cattleya, Phalaenopsis, Dendrobium, Oncidium, Vanda, Paphiopedilum and Brassia.
Does the listing say the mix is organic?
No. The saved bullets do not say organic.
The Westland 4 litre bag is pine bark with Seramis at about £7.29, about £1.82 a litre, and the listing says that volume fills a 14 cm pot. Item weight is 1.16 kg, so it is a light lift for one small repot. The page prints 4.6 from 8,049 ratings, but UK reviews on file include a Miracle-Gro thank-you and a note that a Westland order arrived as Miracle-Gro, so that count is not a clean sample of this listing. Reviewers who do describe the mix report new leaves and flower stems about four weeks after repotting three plants, and longer use on plants several years old. One reviewer found a batch too dense and mixed in extra perlite, and another says the compost holds water and contains some peat, which is a review claim rather than a line on the listing. The saved bullets do not say peat free and do not print a millimetre bark grade. At about £1.82 a litre it costs more per litre than the 8 litre Westland bag in this set, and a best-seller slot in plant root stimulators is not a feed analysis.
Pros
Cons
Best for: You want one 14 cm pot of Westland bark with Seramis and can accept a review file that also names Miracle-Gro.
Less suitable: You need a peat-free line on the Amazon listing, a lower price per litre, or a review sample that only describes this listing.
Specifications
Common questions
What size is this listing?
4 litres. The listing says the bag fills a 14 cm pot. Item weight is 1.16 kg.
Does the listing say peat free?
No. The saved bullets do not say peat free.
Can the 8,049 ratings be read as this bag alone?
The listing prints 4.6 from 8,049. UK reviews on file include a Miracle-Gro thank-you and a substitution note, so the count is not a clean sample of this listing.
The Westland 8 litre potting mix is bark with Seramis clay granules at about £8.40, about £1.05 a litre, and the listed weight is 3 kg. Across 241 amazon.co.uk ratings the line is 4.6, and the notes on file mark this review pool as belonging to this listing, unlike the 4 litre Westland file. Reviewers say their orchids did well after repotting, including one household that had used the mix for years and would order it again. The complaints pull in opposite directions: one review says water did not pass and the roots rotted, another says there were too many fine particles, and a third says water runs through very quickly. The saved bullets do not say peat free, do not print a millimetre grade, and do not state how many pots the bag fills. It is the top pick in this set because 87 is the highest score among listings with at least 50 ratings and a review file of their own. Return postage on an unwanted second bag is a delivery complaint, not a comment on the bark.
Pros
Cons
Best for: You want the strongest own-review bark-and-Seramis bag in this set and you can store 8 litres at 3 kg.
Less suitable: You need the words peat free on the Amazon listing itself, or you only have one 12 cm pot and nowhere to keep the rest of an 8 litre bag.
Specifications
Common questions
What is in the mix on this listing?
Bark and Seramis clay granules, described as an open mix that allows airflow and retains moisture.
Does this Amazon listing say peat free?
No. The saved title and bullets do not say peat free. Westland's UK product page does describe the orchid potting mix as peat free.
What rating does the listing print?
4.6 out of 5 from 241 ratings.
The UK GROW 5 litre listing is orchid bark with perlite at about £9.99, about £2.00 a litre, with an item weight of 1.2 kg. The bullets claim a pH-balanced mix infused with essential nutrients, without an analysis, and they also name bromeliads and tillandsias as well as orchids. The printed line is 4.5 from 395 ratings, and the same opening UK reviews appear on the 1 litre listing, so those reviews are one shared sample rather than a separate test of the 5 litre bag. Praise in that shared file includes a resealable bag, a chunky clean texture on a repeat buy, and perlite that does not hold water for long. The same file also describes a bag that was mostly perlite, bark smaller than the photos, a funny smell on one repeat order, and a pack that only filled a six-inch pot, which may be the 1 litre size. The unit count field says 1.0 gram while the title says 5 litres. The listing does not say peat free and does not print a millimetre grade.
Pros
Cons
Best for: You want a 5 litre bark-and-perlite bag and you treat the 4.5 from 395 as one sample shared with the 1 litre pouch.
Less suitable: You need an own review sample, a peat-free statement on the listing, or a lower price per litre.
Specifications
Common questions
What volume does the listing state?
5 litres in the title and the volume field. The unit count field says 1.0 gram.
Does the listing claim nutrients?
Yes. It says pH-balanced and infused with essential nutrients. It does not print an analysis.
Are the 395 ratings only for 5 L?
The listing shows 4.5 from 395, with the same opening UK reviews as the 1 litre listing.
The UK GROW 1 litre listing uses the same bark-and-perlite title at about £7.99, which is £7.99 a litre, and the item weight is 250 g. The volume field says 1 litre while the unit count field says 1.0 gram, so the pack maths on the page do not agree. The style line calls the mix perlite-rich and nutritional, without a printed analysis, and the saved bullets do not say peat free. The star line is 4.5 from 395 ratings, the same figure as the 5 litre listing, and the opening UK reviews are the same text, so this is not an independent sample of the small pouch. Those shared notes call the mix chunky and easy to work between roots, and they also say one bag was mostly perlite and that the bark looked larger in the photos than in the hand. A reviewer called it a bit expensive for the amount, which matches a price per litre far above the 5 litre listing. If the 1 litre volume field is the one you trust, this pouch is a single small repot, not a collection bag.
Pros
Cons
Best for: You have one small pot, no room for a 5 litre sack, and you will not treat the shared 395 ratings as proof of this pouch alone.
Less suitable: You are repotting more than one plant, or you want a lower price per litre and a review file that belongs to this size.
Specifications
Common questions
What volume does the listing state?
The title says 1 L and the volume field says 1 litre. The unit count field says 1.0 gram, which does not match.
Does the listing say the mix is peat free or organic?
No. Those words are not in the saved bullets. Organic appears only as a question.
Are the 395 ratings unique to this 1 L bag?
The listing shows 4.5 from 395, and the same opening UK reviews appear on the 5 litre listing.
The Miracle-Gro 10 litre bag is pine bark orchid compost at about £6.00, about £0.60 a litre, and it is the only listing in this set whose title and bullets say peat free. The page says that volume fills six 12 cm pots, one 22 cm pot, or one 30 cm hanging basket, and the item weight is 3.62 kg with the United Kingdom given as the country of origin. The bullets claim 11 nutrients, including nitrogen, phosphorus, potassium and trace elements, plus a low pH formula, without a numeric pH, and they do not say the mix is organic. Across 160 ratings the line is 4.5, in a review file marked as this listing's own. Buyers praise the 10 litre size and using the compost to repot into new pots. Others say it is hard to wet without flooding the pots, one review says both plants died after repotting, and one review calls it orchid peat, which clashes with the peat-free title. At about £0.60 a litre it is the best value here, and the listing still does not print a millimetre bark grade.
Pros
Cons
Best for: You want a peat-free line on the Amazon page, a printed feed claim, and the lowest price per litre among the eligible bags.
Less suitable: You only have one small pot and no storage for 10 litres, or you need a bark grade in millimetres rather than the words large pieces.
Specifications
Common questions
Does the listing say this compost is peat free?
Yes. The saved title is Miracle-Gro Peat Free Orchid 10 L, and the bullets repeat peat free.
How many pots does the listing say 10 L fills?
Six 12 cm pots, one 22 cm pot, or one 30 cm hanging basket.
Does the listing say the mix is organic?
No. Organic is only a customer question on the page. The bullets do not say organic.
The UK GROW Elite 10 litre bag is sterilised pine bark with perlite at about £12.99, about £1.30 a litre, and the listed weight is 2.22 kg. The bullets claim the bark is sterilised, pest-free and fungus-free, with heat-sealed packaging and a 12-month limited warranty on materials and workmanship. Those lines are seller claims. The listing prints 4.5 from 9 ratings, and only three UK reviews are on file against that count of nine. Those reviews call it good for mixing with other substrates, excellent, or good value after a couple of months in houseplant mixes. One of them also says the bark was dusty, with twiggy bits that needed a rinse in a colander and a sort-through. Nine ratings are too few for a badge, and the listing does not say peat free or give a millimetre grade. At about £1.30 a litre it costs more than twice the Miracle-Gro 10 litre bag, which does print peat free.
Pros
Cons
Best for: You want a 10 litre bark-and-perlite sack and you will judge the sterilised claim as seller text, not as a large UK review sample.
Less suitable: You want 50 or more ratings on this bag, a peat-free title, or the lower price per litre of the Miracle-Gro 10 litre listing.
Specifications
Common questions
What does the listing claim about pests?
It says the bark is sterilised and pest-free and fungus-free. That is a seller claim.
Does the listing say peat free?
No.
What do the three UK reviews on file say about texture?
One calls it good for mixing. One says excellent. One says dusty with twiggy bits that needed a rinse.
The Black Soil Society 5 litre mix, listed under Invigortex, is chunky pine bark and perlite at about £13.99, about £2.80 a litre, and the title says it is hand blended in the UK. The bullets aim it at Phalaenopsis and other epiphytes and claim fast drainage without general-purpose fillers. The star line is 4.0 from 17 ratings, the lowest in this set, and the notes on file mark the pool as a small sample with a mismatch. Seven UK reviews are on file: some call it good quality and as advertised, while others say it was soil with small bark rather than large chunks, that dust and tiny perlite made about half the bag unusable, and that fungus gnats were in one bag. One review talks about the pack as if it were not 1 litre, which does not match the 5 litre title, and the unit count field says 1,000 grams against a 1.7 kg item weight. The listing says chunky and does not print a millimetre size or peat free. Seventeen ratings, plus that mismatch, keep it off both badges.
Pros
Cons
Best for: You specifically want this 5 litre brand and you will open the bag and reject it if the bark is fines rather than chunks.
Less suitable: You want a larger own review sample, a trustworthy litre field, or a lower price per litre.
Specifications
Common questions
Does the listing name the bark?
Yes. The bullets say premium chunky pine bark with perlite for Phalaenopsis and other epiphytes.
How many UK reviews are on file?
Seven. The listing line says 4.0 from 17 ratings.
Does the listing give a millimetre bark grade?
No. It says chunky and does not print a millimetre size.
Eight amazon.co.uk listings were scored from the stored pages, read on 21 October 2026. Clay pebbles and keiki paste were left out. There is no laboratory trial and no flowering trial. Stars on the listing are worth up to 70 points. The printed review count is worth up to 30, on a log scale capped at 30. A badge needs at least 50 ratings and a review file that belongs to that listing. A shared sample is not a second test, and a file that names another brand is not an own sample. Among listings that pass that gate, Westland Orchid Potting Mix 8 L is the top pick. Miracle-Gro Peat Free Orchid 10 L is the best value, at the lowest price per litre. The score is not a measure of roots or flowers. The weights below sum to 100.
Amazon stars
70%amazon.co.uk stars divided by 5, times 70, then rounded. 4.6 becomes 64. 4.5 becomes 63. 4.0 becomes 56. The star line is not a laboratory test.
Review count
30%Log10 of the printed rating count, times 10, capped at 30. 8,049 ratings cap at 30. 12 ratings score 10. A shared or cross-brand file still uses the printed count, then fails the badge gate.
Match the genus and the litres before you match the star line. Prices below are amazon.co.uk shelf prices on 21 October 2026. This is not a laboratory test and not a flowering trial.
Orchid soil in UK shops is pine bark, or bark with perlite or fired clay granules. It is not garden soil and not multipurpose compost. Buyers are repotting a supermarket moth orchid or a small collection. Quality is a stated volume, a named ingredient list, chips that are still chunky, and a peat-free line only where the pack prints it. Three retail types cover the bags compared here. Graded pine bark, sometimes with perlite. Bark plus fired clay granules, sold as holding and releasing water.
The Royal Horticultural Society says moth orchids need bark-based compost, never loam or multipurpose compost. A pot that is too big, a moss plug left in, and buried aerial roots are the same kind of mistake.
The Westland 4 litre file prints 4.6 from 8,049 ratings and includes Miracle-Gro text. The UK GROW 1 litre and 5 litre listings share 4.5 from 395. A high count is not a trial of one ASIN.
Quote peat free only from the pack or the maker's UK page. Miracle-Gro prints it on the Amazon title. The Westland Amazon bullets in this set do not. An England peat ban announced for 2024 is not in force.
Phalaenopsis and Cymbidium want coarse bark, about 8–15 mm on the BBC Gardeners' World scale. Finer bark, about 5–8 mm, is for other types. Slipper orchids are a different recipe, and a Vanda is grown without compost. None of these listings prints a millimetre grade. Plain or perlite bark, bark plus fired clay, and a nutrient-added compost are different watering and feeding habits. Miracle-Gro's label claims 11 nutrients and says to start orchid feed after four weeks.
A seller rule of thumb is about 1 litre for an 11 cm pot, 5 litres for 14–20 cm, and 10 litres for 20–28 cm. The Westland 4 litre listing says it fills a 14 cm pot. Miracle-Gro says 10 litres fills six 12 cm pots, one 22 cm pot, or one 30 cm hanging basket, and volume may fall by up to 10%. BS EN 12580:2013 is a fill standard, not a quality rank. On 21 October 2026 the large bags sit near £0.60–£1.30 a litre and the 1 litre pouch at £7.99 a litre.
Three typical situations, each with a recommendation from this comparison.
You are repotting one supermarket moth orchid into about a 14 cm pot and you do not want a sack left in a flat. Westland orchid mix with Seramis 4 L is about £7.29 and the listing says that volume fills a 14 cm pot. The item weight is 1.16 kg. The page prints 4.6 from 8,049 ratings, and UK reviews on file also name Miracle-Gro, so that count is not a clean sample of this bag.
You can store 8 litres at 3 kg and you want bark with Seramis clay granules and a review file for that bag. Westland Orchid Potting Mix 8 L is the top pick at about £8.40, about £1.05 a litre, with 4.6 from 241 ratings. Reviewers report plants doing well after repotting. One review says water did not pass and the roots rotted.
You want the words peat free on the Amazon page, a printed feed claim, and the lowest price per litre. Miracle-Gro Peat Free Orchid 10 L is the best value at about £6.00, about £0.60 a litre, with 4.5 from 160 ratings. The listing says the bag fills six 12 cm pots. Reviewers say it is hard to wet without flooding the pots.
The top pick is Westland Orchid Potting Mix 8 L at about £8.40. It is bark with Seramis clay granules, about £1.05 a litre, with 4.6 from 241 ratings on this listing, and it has the highest score among bags with at least 50 ratings and their own reviews. The best value is Miracle-Gro Peat Free Orchid 10 L at about £6.00, about £0.60 a litre, the only bag here whose title and bullets say peat free. The Westland 4 litre file scores higher on stars and count, and the UK GROW 1 litre and 5 litre files sit next, but those review files are not an own sample of one bag. The score is not a measure of roots or flowers.
Miracle-Gro Peat Free Orchid 10 L
Lowest price per litre among bags that pass the same gate: about £0.60 a litre, about £6.00 for 10 litres, with peat free on the title.
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 eight amazon.co.uk listings read on 21 October 2026. A peat-free line is quoted only where the listing or the maker's UK page prints it. A sterilised claim is seller text. Stars are not a laboratory test, and a shared review file is not a second trial.
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.
