The best horticultural vermiculite, compared.
Top pick: PLANT!T vermiculite 100 L – Largest review base in this set, 4.7 from 1,011 reviews, at about £0.43 per litre. Best value: UK GROW vermiculite bag 25 L – £19.99 for 25 L, about £0.80 per litre, with 4.5 from 87 reviews on this listing. Updated October 2026.
If you are sowing seed, mixing peat-free compost or trying to keep a thirsty houseplant from drying out, the vermiculite bag is easy to get wrong. Horticultural vermiculite is heat-expanded mica sold in the UK as light flakes that hold water. It is not perlite, not coir and not a fertiliser. Medium flakes, about 2–5 mm, belong in a mix. A title that lists every litre size is not the volume in the parcel. The [buying guide to vermiculite for plants](/hub/ornamental-plants/vermiculite-for-plants/sub/vermiculite-for-plants-buying-guide) explains those checks before you use the table. Reviewers still call the flakes chunky for a fine seed cover. The RHS peat-free page says there is currently no legislation banning peat in UK horticulture, so these bags do not stand in for compost.
If you are sowing seed, mixing peat-free compost or trying to keep a thirsty houseplant from drying out, the vermiculite bag is easy to get wrong.
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Personal buying guide
Question 1 of 2
How much will you use this season?
The 100 L PLANT!T bag is the top pick in this amazon.co.uk set. It has 4.7 from 1,011 reviews, a far larger base than any other pack here, and the £42.95 shelf price is about 43 pence per litre. Hydrogarden lists the weight at 8.8 kg. The listing does not print a millimetre grade, and reviewers describe the flakes as chunky, closer to perlite, so people still buy a finer grade when the only job is a thin seed cover. That makes the sack a strong buy if you mix compost through the season and can keep a large bag dry. It is a weaker buy for one tray of fine seed, or if you have nowhere dry to store 100 litres. Reviews also mention bags that felt damp and bags that arrived punctured, so check the sack before you tip it into a bin. Compared with smaller pouches at about £1 a litre, the bulk price only pays if you will use the volume.
Pros
Cons
Best for: A grower who will use a large sack through the season and can keep it dry.
Less suitable: Someone covering one tray of fine seed, or without a dry place for 100 litres.
Specifications
Common questions
Is the flake size printed?
This listing does not state millimetres. Reviewers describe the flakes as chunky, similar in size to perlite, and say they still buy a finer grade for seed covering.
How heavy is the 100 L bag?
The technical line says 8.8 kg.
Did bags arrive intact?
Reviews include bags that felt damp and bags that arrived punctured.
This Topline listing is titled as two 10 L Gro-Sure bags at £22.99, while the item-volume line says 10 litres, so you cannot tell the parcel size from the page alone. That clash means there is no reliable price per litre. The grade is not printed on this extract. Fifteen reviews give 4.6, and the two extracted texts are short and positive: pleasant to handle, and that it does the job. There is no criticism in those two texts, and fifteen reviews is a thin base next to the bulk bags. The listed weight is 7 kg. Order it only after you have confirmed whether one bag or two will arrive. Leave it if you need a clear litre price, or a larger set of buyer comments, before you pay.
Pros
Cons
Best for: A buyer who confirms whether one bag or two will arrive before paying £22.99.
Less suitable: Anyone who needs a settled litre price, a printed grade, or a large review base.
Specifications
Common questions
Is this one bag or two?
The title says a pack of two 10 L Gro-Sure bags. The item-volume line says 10 litres. Both figures are left as printed.
What do reviewers say?
The extract has two review texts. Both are positive: pleasant to handle, and that it does the job. There is no criticism in those texts.
The 20 L UK GROW bucket costs £19.99, about £1 a litre, and the lid matters if you keep vermiculite on a windowsill between sowings. The 4.5 score from 406 reviews is shared with the 5 L listing, including the same review text, so that figure is not evidence about this bucket alone. Millimetres are not stated, and reviewers say the particles are larger than fine garden-centre vermiculite, with dust in the tub. The seller frames the job as holding moisture in dry soil. The technical line lists 2.74 kg, while the unit-count line prints 10.0 gram, which is not the volume. Choose it if you want a resealable mid-size tub and will look at the flakes before you cover seed. Leave it if you need a printed grade, or a price per litre closer to the bulk bags. A shared star rating can look stronger than a smaller listing that is actually about one bag.
Pros
Cons
Best for: A windowsill grower who wants a lidded tub and will check the flake size before sowing.
Less suitable: Anyone who needs a stated grade, or who will mix enough compost to justify a cheaper bulk bag.
Specifications
Common questions
Does the 406-review score belong only to the 20 L bucket?
No. The 5 L listing carries the same 4.5 from 406 ratings and the same review text.
What grade is in the bucket?
Millimetres are not stated. Reviewers say the particles are larger than fine garden-centre vermiculite.
Is the unit count the volume?
Volume is 20 litres and weight is 2.74 kg. The unit-count line prints 10.0 gram.
The 5 L UK GROW bucket is the small resealable option at £11.99, about £2.40 per litre, the dearest pure vermiculite rate in this set. The 4.5 from 406 ratings matches the 20 L bucket, and the review text matches too, so those ratings are one parent listing. No millimetre grade is printed. The seller says the flakes can hold up to four times their weight in water, and that sentence is not a test certificate. The listed weight is 658 g, while the unit-count line prints 10.0 gram. It is useful if you only cover a few trays and want a lid between sessions. It is poor value if you already know you will mix compost all spring, because the 25 L bag and the 100 L sack cost much less per litre. Treat the star line as a family score, then judge this tub on the flakes you pour out.
Pros
Cons
Best for: Someone covering a few trays who wants a lid and will not need litres all season.
Less suitable: A grower mixing compost through spring, who will pay much less per litre in a larger bag.
Specifications
Common questions
Are the 406 reviews about this 5 L bucket alone?
The review text and the 4.5 from 406 ratings match the 20 L bucket. They are one parent listing.
Is a grade stated?
No millimetre grade is printed. The seller says the flakes can hold up to four times their weight in water. That sentence is not a test certificate.
The 25 L UK GROW bag is the best value in this set. At £19.99 it is about 80 pence per litre, and 4.5 from 87 reviews is a count on this listing rather than a score borrowed from another size. The grade is not stated, so you should not treat it as a fine seed cover until you see the flakes. Reviews praise moisture around seedlings. One review reported sunflower and wheat seeds growing in bulb pots, and one buyer received a plastic box instead of a sealed bag. The technical line says 1 x 1 x 1 cm and 10 kg, which cannot describe a 25 L sack, so ignore that measurement. It suits someone who wants more than a bucket and less than 100 L, and who will check the contents on arrival. It is less suitable if you need a stated millimetre range or a branded pouch with a printed particle size.
Pros
Cons
Best for: A buyer who wants a reviewed mid-size bag and will inspect the flakes before sowing.
Less suitable: Anyone who needs a printed millimetre grade, or a sealed branded pouch with a stated particle size.
Specifications
Common questions
Are the printed dimensions the bag size?
The technical line says 1 x 1 x 1 cm and 10 kg. A 1 cm cube is not a 25 L bag, so that line is not a usable measurement.
What do the reviews say about the contents?
Reviews praise seedling moisture. One review reported sunflower and wheat seeds growing in bulb pots, and one buyer received a plastic box instead of a sealed bag.
This PLANT!T listing is a 25 L portion boxed from a trade bag, at £22.99, about 92 pence per litre, with 4.4 from 47 reviews. The bullets say you receive 25 L, not 100 L, even though the title still lists 100, 50, 25, 10 and 5 litres. Reviews say the picture implied 100 L. Packing notes describe a black bin bag, a damaged bag, and vermiculite that looked shovelled from a larger pile. The listed weight is 3.64 kg. The grade is not stated, and the main job line on the comparison is empty. It can be a smaller volume of the same brand if the seller actually sends 25 L. It is a poor choice if you are buying on the 100 L figure in the title, or if you want a sealed retail sack with a printed grade.
Pros
Cons
Best for: A buyer who has read the 25 L bullets and wants a smaller portion of this brand.
Less suitable: Anyone ordering from the 100 L figure in the title, or who wants a sealed retail bag with a printed grade.
Specifications
Common questions
Is this the 100 L bag?
The bullets say you receive 25 L boxed from a large trade bag, not 100 L. The title still lists 100, 50, 25, 10 and 5 litres. Reviews say the picture implied 100 L.
How is it packed?
Reviews describe a black bin bag, a damaged bag, and vermiculite that looked shovelled from a larger pile. Weight on the listing is 3.64 kg.
The 50 L UK GROW bag is £29.99, about 60 pence per litre, which undercuts the 25 L bag on price. The listing shows 4.4 from five ratings, and the extract contains no review text, so there is no buyer account of flake size, dampness or fill. The grade is not stated. The seller says the vermiculite is pH neutral, and that line is not a laboratory report. The listed weight is 6 kg, while the unit-count line prints 1.0 gram. The stated jobs are seed covering and compost amendment. The low price per litre is attractive if you need volume and can inspect the bag yourself. Five ratings without text are not enough to call it the best value beside the 25 L bag, which has 87 reviews you can actually read.
Pros
Cons
Best for: A buyer who wants volume at a low per-litre price and will inspect the bag on arrival.
Less suitable: Anyone who wants written reviews before choosing, or a printed grade for seed covering.
Specifications
Common questions
Is the pH stated as a test result?
The listing says the vermiculite is pH neutral. That is a seller sentence. No laboratory report is attached.
What do buyers say?
The listing shows 4.4 from 5 ratings. The extract contains no review text, so praise and complaints are not available.
This 0.5 L B2C pack is the small bag that prints a grade, 2 to 8 mm, which is a mixed flake rather than a fine seed cover. At £3.38 it is about £6.76 per litre, several times the rate of the bulk bags. The rating is 4.2 from 74 reviews. One reviewer said the flakes felt soft, like shredded tin foil, compared with a shop bag. The selected variant is 500 ml, though the title also lists larger sizes. Item weight is not stated, and the unit-count line prints 100.0 gram. It fits a single pot or a texture trial before you buy litres. It is a poor way to fill seed trays or to amend a sack of compost, because the price per litre climbs so fast at this size.
Pros
Cons
Best for: Someone trying the texture in a single pot before buying a larger bag.
Less suitable: Anyone filling seed trays or amending a sack of compost, where the price per litre is far too high.
Specifications
Common questions
How much vermiculite is in the pack?
The selected variant is 500 ml. The title also lists larger sizes. Item weight is not stated; the unit-count line prints 100.0 gram.
What grade is it?
The title says 2 to 8 mm. One reviewer said the flakes felt soft, like shredded tin foil, compared with a shop bag.
The 10 L Swiftair bag costs £8.99, about 90 pence per litre, and the title prints a grade of 2.0–5.0 mm. One bullet says coarse vermiculite and another says fine vermiculite, so the page disagrees with itself. The model number is SW-VERMIC-100L and the part number is SW-VERMIC-10L, which does not help you judge the flakes. The listed weight is 800 g. There is no customer-review line, so nobody on the extract has confirmed that the contents match the title range. A stated millimetre band is still more than most bags here offer, if you want medium flakes for potting. Open the bag before you rely on it as a thin seed cover, because 2.0–5.0 mm is not a fine grade and the bullets contradict each other. It is a weak choice if you need reviewed buyer comments before you order.
Pros
Cons
Best for: A buyer who wants a stated medium grade for potting and will open the bag to check it.
Less suitable: Anyone who needs reviews before ordering, or a clearly fine grade for a thin seed cover.
Specifications
Common questions
Is this fine or coarse?
The title says 2.0–5.0 mm. One bullet says coarse vermiculite and another says fine vermiculite. The model number is SW-VERMIC-100L and the part number is SW-VERMIC-10L.
Are there reviews?
The extract has no customer-review line.
This 100 L B2C bag is a blend, not pure vermiculite. The listing says half perlite and half vermiculite, grade 1–8 mm, at £32.49, which is about 32 pence per litre of mix. Packs are sold by litres, not kilograms, and the item weight is not stated. There is no customer-review line, so the low rate is not backed by buyer comments in the extract. A 1–8 mm span is a mixed flake, too wide for a thin seed cover. The blend can suit you if you want air from perlite and moisture from vermiculite in one sack for seeds, cuttings and potting mixes. It is the wrong bag if you wanted pure vermiculite, or if you need reviews before you commit to 100 L. Do not read the 32 pence figure as a pure-vermiculite price, because half the volume is perlite.
Pros
Cons
Best for: A grower who wants both minerals in one sack for seeds, cuttings and potting mixes.
Less suitable: Anyone who wanted pure vermiculite, a fine seed cover, or reviews before buying 100 L.
Specifications
Common questions
Is this pure vermiculite?
No. The listing says 50% perlite and 50% vermiculite, grade 1–8 mm.
Does 100 L mean 100 kg?
The listing says packs are sold by litres, not kilograms. Item weight is not stated. There is no customer-review line.
We compared ten vermiculite listings on amazon.co.uk and set them against public UK sources, including RHS guidance. Scores use the printed grade, the litres you can confirm, price per litre, and whether the review count belongs to that variant. This is not a laboratory test.
Grade for the job
30%Fine flakes cover seed. Medium flakes, about 2–5 mm, belong in a mix. If the listing prints no millimetres, the grade is unknown until the bag is open.
Litres on the selected variant
20%The volume is the selected variant, not the largest number in a multi-size title. A title that lists every size is not the parcel.
Pure vermiculite or a blend
15%A 50/50 perlite and vermiculite sack is a mix. Its price per litre is not a pure-vermiculite price.
Price per litre and review evidence
25%Price per litre is arithmetic from the shelf price. A star line only counts when the reviews are about that variant.
Dry storage and arrival condition
10%Reviews describe punctures, damp sacks and dust. A large bag only pays if you can keep it dry and will use the volume.
Match the flake to the job before you compare stars. Fine vermiculite covers seed. Medium vermiculite, about 2–5 mm, belongs in a potting or cuttings mix. Read the litres on the variant you select, then the price per litre, then whether the reviews are about that pack. A wide millimetre range is a mixed flake. A 50/50 bag is not pure vermiculite. None of these extracts is a lab report, and none prints an RHP mark.
Horticultural vermiculite is heat-expanded mica. In UK garden use it is sold as light flakes that hold water in seed trays, cuttings compost and potting mixes. Buyers are sowing seed, amending peat-free compost, or trying to keep a thirsty houseplant from drying out. It is an amendment, not a peat replacement and not a fertiliser. The RHS peat-free page says there is currently no legislation banning peat in UK horticulture, so these bags do not stand in for compost. Grade decides the job.
Fine flakes cover seed. Medium flakes, about 2–5 mm, belong in a mix. A 2–8 mm or 1–8 mm range is a mixed flake. RHS Wisley says to use grit, not vermiculite, when germination takes about 60 days or longer.
The litres are the selected variant. The PLANT!T split listing is 25 L boxed from a trade bag, while reviews say the picture implied 100 L. Topline's title says two 10 L bags and the item-volume line says 10 litres.
Dampen flakes and tip them in moving air. Vermiculite does not feed plants and does not replace compost. It is a poor main amendment for cacti and succulents. Keep the sack dry so it does not arrive, or sit, damp.
The first check is the flake size for the job you actually have. Fine vermiculite, often sold around 0–2 mm or 1–3 mm, is the type that covers seed. Medium vermiculite, often about 2–5 mm, belongs in a potting or cuttings mix. A title that spans 2–8 mm or 1–8 mm is a mixed flake. It is not a fine seed cover. If the listing prints no millimetres, the grade is unknown until the bag is open.
The second check is how many litres you will actually receive, what that costs per litre, and whether the stars are about that variant. Read the selected variant, not the largest number in a multi-size title. The PLANT!T split listing is 25 L boxed from a trade bag, and reviews say the picture implied 100 L. Topline's title says two 10 L bags while the item-volume line says 10 litres, so there is no reliable price per litre.
Three typical situations, each with a recommendation from this comparison.
You will mix compost through the season and you have a dry place for a large sack. PLANT!T 100 L is the top pick here: 4.7 from 1,011 reviews and about £0.43 per litre. Reviewers still call the flakes chunky for a fine seed cover, so look at the grade before you use it as a thin cover.
You want a resealable tub between sowings, not a 100 L sack. The 20 L UK GROW bucket holds a mid volume and the lid keeps dust in. The 4.5 from 406 reviews is shared with the 5 L listing, and no millimetre grade is printed, so check the flakes before you cover seed.
You want more than a bucket and less than 100 L, with reviews that belong to this listing. The UK GROW 25 L bag is the best value in this set, at £19.99, about £0.80 per litre, with 4.5 from 87 reviews. The grade is not stated, so inspect the flakes before sowing.
PLANT!T vermiculite 100 L is the top pick if you will use a large sack and can keep it dry: 4.7 from 1,011 reviews and about £0.43 per litre. It is a weaker buy for a thin seed cover, because reviewers call the flakes chunky and the grade is not printed. The UK GROW 25 L bag is the best value at £19.99, about £0.80 per litre, with 4.5 from 87 reviews on that listing. Check the flakes on arrival, and do not buy from the largest number in a multi-size title.
PLANT!T vermiculite 100 L
Largest review base in this set, 4.7 from 1,011 reviews, at about £0.43 per litre.
UK GROW vermiculite bag 25 L
£19.99 for 25 L, about £0.80 per litre, with 4.5 from 87 reviews on this listing.
Editorial
Products Compared publishes British-English buying guides based on amazon.co.uk listings and public UK sources. We do not run a lab and we do not invent test scores.
Guides on what to look for, how to use a product, and common mistakes.
Public sources used for this comparison. Prices are amazon.co.uk shelf prices from the listing extracts dated 15 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. If you buy through them we may earn a commission at no extra cost to you. The notes use listing details and public UK sources. We did not run a lab test.
