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Compost vs topsoil for raised beds

Updated: October 2026

You have a new timber frame on the lawn or on paving, and one bag looks as if it could fill the box. Compost vs topsoil for raised beds decides whether that surface stays through the season. Compost adds organic matter and then breaks down. Topsoil is the mineral body that holds the level. The [raised bed compost comparison](/hub/raised-beds-greenhouses-and-compost/raised-bed-compost) lists six multi-purpose bags, and none is sold as topsoil. For a new bed, use both, with soil as the larger share. A waste-derived load is a specialist question, not another sack.

You have a new timber frame on the lawn or on paving, and one bag looks as if it could fill the box. Compost vs topsoil for raised beds decides whether that surface stays through the season.

Our top picks

Munnie Munnie multi-purpose compost 60 L

Best overall

Munnie Munnie multi-purpose compost 60 L
7.3/10about £9.34
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ecoblaze TerraGrade multipurpose compost 60 L

Rank 2

ecoblaze TerraGrade multipurpose compost 60 L
7.3/10about £10.99
View offer
GROWMOOR Growmoor multi-purpose compost 60 L

Rank 3

GROWMOOR Growmoor multi-purpose compost 60 L
7.8/10about £13.98
View offer
On this page
  1. 1.Two materials, two jobs
  2. 2.The parts in one bed
  3. 3.What you can buy in this set
  4. 4.Bulk topsoil and when to ask for help

Two materials, two jobs

Multi-purpose compost is a light potting medium. It holds water and feed in a pot for a season, then it breaks down and the volume falls. The Royal Horticultural Society fills a vegetable bed mainly with soil, because garden compost and potting compost both slump. Topsoil is the heavier mineral part. It keeps the height after the organic share settles. Use compost for pots and small top-ups, and topsoil where the frame is deep.

The parts in one bed

On ordinary ground the RHS uses seven parts topsoil, three parts organic matter, and two parts horticultural sharp sand. The organic matter is garden compost, leafmould, or well-rotted manure, and topsoil is the largest share. On paving the sand rises to four parts, while topsoil stays at seven and organic matter at three. A frame 1.2 metres by 0.6 metres by 0.3 metres holds 216 litres, and the organic share is 54 litres, about one 60 litre bag. The how to fill a raised bed page works the paving sum.
Munnie Munnie multi-purpose compost 60 L

Testsieger

Munnie Munnie multi-purpose compost 60 L
7.3/10about £9.34
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What you can buy in this set

Munnie, TerraGrade, the three Growmoor packs, and Laeto are multi-purpose compost. None is titled topsoil, and none is sold to BS 3882:2015, the standard for traded topsoil rather than soil left in the ground. Laeto's bullets say the blend combines topsoil and soil improver. It is still 240 litres of compost at £41.63, and peat-free is not stated. TerraGrade tells you to blend its compost with quality topsoil for delicate seeds, so the soil is still to buy. Place each bag on the which bag suits which job page, and peat wording on the peat-free raised bed compost page.

Bulk topsoil and when to ask for help

RPS 190, updated on 12 October 2026, says manufactured topsoil from waste must be made to BS 3882:2015 at a permitted site, and it can still be waste. If the quote mentions waste or RPS 190, ask a specialist.

Common questions

Can I fill a raised bed with compost and skip topsoil?
You can, and plants will grow for a while. The RHS still wants a vegetable bed filled mainly with soil, because compost slumps and you buy more to recover the level. Compost alone fits a pot, or a topping on soil already in the frame. In a new bed, skip topsoil only if you can accept a lower surface later.
What does topsoil do that compost does not?
Topsoil holds the weight and the height after organic matter has rotted. Compost feeds the bed and holds moisture, then it shrinks. Without soil, the fill keeps settling. Without compost, soil can be hungry and tight, especially a stony economy grade.
What is the RHS split in parts?
On ordinary ground it is seven parts topsoil, three parts organic matter, and two parts horticultural sharp sand. The organic matter is garden compost, leafmould, or well-rotted manure. On paving, sand rises to four parts and the other shares stay put. A half-and-half American mix is a different method. Use twelve parts unless the bed is on a hard surface, where sand is the share that changes.
Is a topsoil sentence on a compost bag the same as buying topsoil?
No. Laeto says the blend combines topsoil and soil improver, and the listing is still 240 litres of compost at £41.63, not topsoil sold to BS 3882. TerraGrade tells you to add quality topsoil for delicate seeds. Read the title, not a bullet that borrows the word. If you need mineral soil, buy a product that is sold as topsoil.
What should I ask for on a bulk load?
Ask for topsoil to BS 3882:2015, the grade, and a declaration of analysis. Premium suits vegetables. Economy can go under turf and is a poor main fill if it is full of stone. Check the cubic metres against the bed so the load is not short. If the seller will not name the grade, choose another supplier.
Does BS 3882 mean the soil is not waste?
No. The standard covers traded topsoil, including manufactured topsoil. Under RPS 190, topsoil made from waste must meet BS 3882:2015 at a permitted site and can still be waste. The mark is not a clean-soil certificate. Waste-derived loads, and ground that may be contaminated, need a specialist rather than another bag.
Which of these six bags is topsoil?
None of them. Munnie, TerraGrade, the Growmoor 60 litre, twin, and 180 litre listings, and Laeto are multi-purpose compost. Laeto's topsoil sentence does not make it a BS 3882 product. Buy soil from a topsoil supplier, and use these bags for the organic share or for pots.

Related pages

Raised bed compost buying guide

Raised bed compost

Best compost for raised beds: which of these six bags fits

How to fill a raised bed: RHS depth, parts and litres

Peat-free compost for raised beds and the words that count

Sources

Public UK sources for the mix, peat wording and sale-of-goods rules. Listing prices and review counts are amazon.co.uk figures from 16 October 2026.

  1. RHS: How to make a raised bed (retrieved 16 October 2026)
  2. RHS: Growing veg in raised beds (retrieved 16 October 2026)
  3. RHS: Peat-free for gardeners (retrieved 16 October 2026)
  4. GOV.UK: Sale of horticultural peat to be banned (retrieved 16 October 2026)
  5. Defra written answer, 19 March 2026 (retrieved 16 October 2026)
  6. BSI PAS 100:2018, specification for composted materials (retrieved 16 October 2026)
  7. GOV.UK: Use of manufactured topsoil (RPS 190) (retrieved 16 October 2026)
  8. Consumer Rights Act 2015, section 11 (retrieved 16 October 2026)