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Horticultural perlite buying guide: grade and litres

Updated: October 2026

When you compare horticultural perlite on amazon.co.uk, the largest bag photograph, the selected variation and the review total may describe different things. A horticultural perlite buying guide therefore starts with the printed particle grade and stated litres, then checks price per litre and whether the star line belongs to that exact size. Our [perlite for plants comparison](/hub/fertiliser-soil-and-bark-mulch/perlite-plants) lists the twelve options. This page explains how to read them. By the end, you should be able to tell a specified 2–5 mm bag from an ungraded bargain, and avoid paying for bulk you cannot store.

When you compare horticultural perlite on amazon.co.uk, the largest bag photograph, the selected variation and the review total may describe different things.

Our top picks

Swiftair Swiftair Perlite 50L, 2–5 mm

Best overall

Swiftair Swiftair Perlite 50L, 2–5 mm
9.5/10about £15.00
View offer
B2C B2C premium perlite, 10 litre

Alternative

B2C B2C premium perlite, 10 litre
9.4/10about £8.79
View offer
Unbranded Horticultural perlite, 100 litre bag

Best value

Unbranded Horticultural perlite, 100 litre bag
6.6/10about £24.95
View offer
On this page
  1. 1.Read the grade before the word premium
  2. 2.Litres, settlement and the product photograph
  3. 3.Compare price per stated litre with storage
  4. 4.Shared stars, missing fields and a final check

Read the grade before the word premium

Particle size tells you more than premium or professional. Sinclair’s table defines Standard horticultural perlite as 2–5 mm and Super Coarse as 3–6 mm. Swiftair’s 50-litre and 100-litre titles print 2–5 mm, and the 10-litre bullet does too. B2C states 1–6 mm, which can mix fine and coarse pieces without proving the bag. The 50/50 pouch states 1–8 mm for the blend, not a straight perlite grade. PLANT!T, the unbranded 100-litre bag, UK GROW 20 litres and the Invigortex pouch print no band. A grade on another shop’s page is not evidence for this amazon.co.uk listing. If grade matters, choose a listing that prints it. The best perlite for plants page applies that check to the leading bags.

Litres, settlement and the product photograph

Perlite is sold by volume because it is very light. A settled bag can look short. Grow Chem says its bags still hold the stated filled volume after settlement. Check the variation and title. B2C says packs under 100 litres are split into clear zip bags and that the 100-litre image is only a reference, so a 10-litre choice can still show the large sack. Ignore unusable fields: a 500 g unit count on a Swiftair 10-litre title, 9,999,999 g on Invigortex, and a UK GROW part number that says perlite 100L on a 20-litre title. If the bag is measurably short, photograph it and contact the retailer. The Consumer Rights Act 2015 requires goods to be as described.
Swiftair Swiftair Perlite 50L, 2–5 mm

Testsieger

Swiftair Swiftair Perlite 50L, 2–5 mm
9.5/10about £15.00
View offer

Compare price per stated litre with storage

Here, 1-litre pouches are about £4.95–£5.50 per litre, 10-litre bags about £0.80–£0.88, Swiftair 50 litres £0.30, and 100-litre choices about £0.25–£0.29. That uses advertised volume and the recorded shelf prices. If you need about 750 ml, a £4.95 pouch can cost less overall than a £15 sack you cannot store. Keep the bag dry, sealed and away from garden chemicals. The UK GROW 20-litre bag at £16.95 is about £0.85 per stated litre, dearer per litre than some 10-litre options. Divide price by the litres in your basket.

Shared stars, missing fields and a final check

Swiftair’s 50-litre and 100-litre listings both show 4.6 stars from 1,502 reviews. Three B2C sizes share 4.4 from 564. That is family-level evidence, not a count for your exact volume. No review line is not proof of a poor product. The £4.95 Invigortex pouch and the £5.50 blend have none, and stars cannot fill in a missing grade. Before you order, confirm straight perlite or a blend, read the millimetre band, check the selected litres, divide price by litres, and see whether reviews mention your variation. The perlite versus vermiculite guide helps if you have not chosen the mineral.

Common questions

Is 2–5 mm perlite coarse or standard?
Sinclair labels 2–5 mm as Standard and 3–6 mm as Super Coarse. Other suppliers may use different names, so compare the numerical band. A 2–5 mm bag is a documented general horticultural grade, but not the same as a specialist coarse orchid product.
Why is one litre almost as expensive as ten litres?
Small pouches carry packaging, handling and delivery costs across very little material. In these listings, one litre was about £4.95–£5.50, while 10-litre bags were about £0.80–£0.88 per litre. The pouch may still cost less overall if you only need one pot.
Does a 100-litre photograph mean I receive 100 litres?
No. The selected variation and title determine the stated order. B2C explicitly uses its 100-litre image as a reference for smaller clear-bag packs. Check the basket before paying and retain the order description if the page uses one photograph for several sizes.
Can I trust 1,502 reviews on both Swiftair sizes?
Treat them as product-family evidence, not 1,502 independent reviews of each size. The identical rating and count on the 50-litre and 100-litre files indicate a shared variation line. Read review text that names the pack received.
Is organic gardening a certification?
Not by itself. A marketing highlight containing organic gardening does not identify a certification scheme or certifying body. If certification matters, look for a named standard and verifiable licence rather than inferring it from a phrase.
When can a 20-litre bag be worse value than ten litres?
When its price per litre is higher. The £16.95 UK GROW 20-litre listing was about £0.85 per litre, while some 10-litre options were around £0.80. Always calculate the exact variation instead of assuming a larger pack has a bulk discount.
What should I do if a bag is obviously short?
Record the selected listing, packaging and your measurement, then contact the retailer. Settlement can alter appearance, but a measured shortfall is different. Goods sold in the UK must be as described under the Consumer Rights Act 2015.

Related pages

Perlite for houseplants

Perlite for plants

Best perlite for plants UK: which bag fits the job

How to use perlite in compost: ratios that fit the job

Perlite vs vermiculite: drainage or water-holding flakes

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 twelve stored amazon.co.uk listings. A shared star line is not a separate sample for each size. Dust warnings are from the cited safety sheets. No exposure was measured at home, and this is not a laboratory test.

  1. RHS, houseplant growing media (retrieved October 2026)
  2. BBC Gardeners' World, what is perlite (retrieved October 2026)
  3. Westland Gro-Sure Perlite (retrieved October 2026)
  4. Vitax Perlite safety sheet (retrieved October 2026)
  5. HSE INDG463, respirable crystalline silica (retrieved October 2026)
  6. AHDB, growing media and liquid feed (retrieved October 2026)
  7. Sinclair perlite grades (retrieved October 2026)
  8. Consumer Rights Act 2015 (retrieved October 2026)