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Compo potting compost: what to read before you buy

Updated: October 2026

You have five Compo bags open in amazon.co.uk tabs, and the photos all show a healthy plant in a pot. Compo potting compost in this set is bagged growing medium for containers, not garden-heap compost and not a bottle of liquid feed. The listings saved on 19 October 2026 run from 5 litres to 12 litres and from £16.92 to £27.43. The picture will not tell you the litres, whether that title says peat-free, or how many weeks of feed that page prints. Shelf prices sit on the [Compo potting compost comparison](/hub/fertiliser-soil-and-bark-mulch/compo-potting-compost). Peter F. used those saved listings. This is not a laboratory test.

You have five Compo bags open in amazon.co.uk tabs, and the photos all show a healthy plant in a pot.

Our top picks

Compo Compo Sana Confort universal 12 L

Best overall

Compo Compo Sana Confort universal 12 L
5.4/10about £16.92
View offer
Compo Compo Sana potting soil 5 L

Rank 2

Compo Compo Sana potting soil 5 L
7.7/10about £20.29
View offer
Compo Compo peat-free bio universal 7.5 L

Alternative

Compo Compo peat-free bio universal 7.5 L
5.0/10about £26.41
View offer
On this page
  1. 1.Litres before the photo
  2. 2.Peat words on this listing
  3. 3.The feed line that belongs to that bag
  4. 4.Price per litre and the weight field

Litres before the photo

Start with the litres, because that is the fact the photograph hides. A 5 litre bag is a flat or a couple of houseplants. A geometry rule of thumb, not a weighed test, puts a 20 cm pot about 16 cm deep near 5 litres. One UK reviewer of the 5 litre Sana bag used two of those bags for a 30 cm pot. The 12 litre Sana Confort is the biggest volume here. The green-plants-and-palms bag is another 5 litres, and the peat-free title is 7.5 litres. If the job is indoor foliage, the houseplant guide separates the palm title from the universal bags.

Peat words on this listing

Only one title in these five says peat-free. That is the 7.5 litre bag sold as Tom Garden Compo Peat-Free Bio Universal, with part 11224. The Royal Horticultural Society's buying tip is to treat a bag that does not say peat-free as not peat-free. The word organic, or bio, does not do that job for you. COMPO's international Sana page describes responsibly produced peat. That page is not the amazon.co.uk bullets. Bio on the 7.5 litre title is not a Soil Association number in the saved listing, and the manufacturer field reads TOM-GARTEN. Whether a UK ban is in force belongs on the peat-free page.
Compo Compo Sana Confort universal 12 L

Testsieger

Compo Compo Sana Confort universal 12 L
5.4/10about £16.92
View offer

The feed line that belongs to that bag

Read the weeks on the listing you are about to pay for, not on a cousin page. The 5 litre and 10 litre Sana bullets say nutrients for up to 6 weeks. The green plants and palms bullet says 8 weeks of nutrition. Those are different claims. The 12 litre UK bullets and the 7.5 litre UK bullets state no weeks. A Spanish review says the page claimed 12 weeks and the bag said 6 weeks. That note is from Spain, and this file does not settle it. Copy the figure from the tab in front of you.

Price per litre and the weight field

In this snapshot the rates are about £4.06 a litre for the 5 litre Sana, £2.74 for the 10 litre, £1.41 for the 12 litre, £4.12 for the foliage bag, and £3.52 for the peat-free bag. The 12 litre bag is the lowest rate and the thinnest page: no feed window, and a saved review sample entirely from Spain. Item weight is 800 g on the 5 litre and 10 litre Sana, against unit counts of 1,970 g and 3,830 g. Who should still open that 12 litre listing is the job of the best page.

Common questions

How many litres do I need for one houseplant?
A 5 litre bag is the usual match for one modest pot or a couple of small ones. A rule of thumb, not a lab measure, puts a 20 cm pot about 16 cm deep near 5 litres. One UK reviewer needed two 5 litre Sana bags for a 30 cm pot. The 10 litre and 12 litre bags are for more than one container, or for a larger pot, and they are a storage problem in a small flat if you cannot close the sack.
Which of these bags says peat-free?
Only the 7.5 litre title, Tom Garden Compo Peat-Free Bio Universal, says peat-free. The Sana listings in this set do not. The Royal Horticultural Society's tip is to treat a bag that does not say peat-free as not peat-free. COMPO's international Sana page talks about responsibly produced peat, and that sentence is not the UK bullet text. Bio on the title is not a Soil Association number in the saved listing.
Are "up to 6 weeks" and "up to 8 weeks" the same claim?
No. Up to 6 weeks is the bullet on the 5 litre and 10 litre Sana listings. Eight weeks is the bullet on the green plants and palms listing. The 12 litre and 7.5 litre UK pages state no weeks at all. An international COMPO page that says 8 weeks, or a seller abroad that says 12, is a different text. Use the weeks on the listing you are buying, then feed as you normally would once that window ends.
Why is the 12 litre bag the cheapest per litre and still a weak listing?
It is £16.92 for 12 litres, about £1.41 a litre, which is the lowest rate in this set, and the listed weight of 3.44 kg does not clash with itself. The UK bullets still give no feed window and no peat line. Every review in the raw sample of 50 is from Spain. A low price per litre is a real advantage if you can accept those gaps. It is not evidence that the page answered the questions a UK shopper asks.
Can I trust the 800 g weight?
No. On the 5 litre Sana the item weight is 800 g and the unit count is 1,970 g. On the 10 litre Sana the item weight is again 800 g and the unit count is 3,830 g. The page is contradicting itself. Do not plan a parcel, a shelf, or a mix ratio around 800 g. The 12 litre, foliage, and peat-free listings print 3.44 kg, 1.98 kg, and 3.17 kg, which at least agree with a bag of damp compost.

Related pages

Compo potting compost comparison

Best Compo potting compost

Compo peat-free compost

Compo potting compost for houseplants

How to use Compo potting compost once the bag is home

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 five amazon.co.uk listings captured on 19 October 2026. A UK peat ban is not in force. German and Spanish review samples are not British customer experience. Bio on the 7.5 litre title is not a Soil Association number in the saved listing.

  1. Defra, sale of horticultural peat to be banned (retrieved 19 October 2026)
  2. RHS, retail peat-free from 2026 (retrieved 19 October 2026)
  3. Baroness Hayman letter, 29 January 2026 (retrieved 19 October 2026)
  4. Horticultural Peat (Prohibition of Sale) Bill (retrieved 19 October 2026)
  5. RHS, fungus gnats (retrieved 19 October 2026)
  6. RHS, growing plants in containers (retrieved 19 October 2026)
  7. COMPO SANA universal potting soil (retrieved 19 October 2026)
  8. COMPO BIO universal potting soil (retrieved 19 October 2026)