In short: "Multipurpose compost" is the UK's everyday name for general-purpose bagged growing media — and since the peat-free shift it is usually a blend of wood fibre, green compost and coco coir. Coco coir on its own is not a complete multipurpose compost, because it contains very few nutrients — but paired with a feed, or blended 50:30:20 with compost and perlite, it does the same job for less money per litre, with better re-wetting and no peat.
What "multipurpose compost" actually means
There is no legal definition of "compost" on a UK garden-centre shelf. In practice the word covers two different things: garden compost you make in a heap, and bagged growing media sold for containers, borders and seed trays. "Multipurpose" simply signals a general-purpose blend — one bag intended to handle most jobs reasonably well.
For decades that bag was mostly peat. With the UK's voluntary move away from peat — B&Q's own-brand ranges peat-free since 2023, Kew peat-free from the end of 2025, and the RHS peat-free for amateur growing media from January 2026 — the recipe has changed, and it is worth knowing what is now inside the bag.
What's inside a peat-free multipurpose bag in 2026
| Ingredient | What it does | Worth knowing |
|---|---|---|
| Wood fibre | Bulk and structure | Can lock up nitrogen as it breaks down — quality blends compensate with added feed |
| Green compost | Nutrients and biology | Recycled garden waste; quality varies between batches |
| Coco coir | Water retention and air structure | The ingredient that makes peat-free blends behave like peat — holds moisture, re-wets easily |
| Bark fines | Drainage | Common in cheaper blends |
| Added fertiliser | 4–6 weeks of feeding | The difference between a "complete" compost and a base medium |
Notice something? Coco coir is already in the bag. Most premium peat-free multipurpose composts lean on coir for exactly the properties gardeners used to buy peat for. Buying coir directly simply cuts out the middle step.
Is coco coir a multipurpose compost?
Not on its own — and any honest supplier should say so. Pure coco coir is a growing medium base: it provides outstanding water retention, drainage and root structure, but it contains very few nutrients. A seedling will establish in it; a fruiting tomato will not thrive without feeding.
That is why we describe our 5 kg buffered coco coir brick as the peat-free alternative to multipurpose compost rather than a compost itself. Used properly, it replaces the bag — you just decide how the nutrients arrive:
- Blend it: our standard 50:30:20 mix (coir : compost : perlite) produces a general-purpose growing medium comparable to a premium multipurpose compost — see our mix ratio guide.
- Feed it: use coir straight for containers and hydroponics with a complete liquid feed from day one.
- Buy it ready-made: three of our plant-specific mixes — Houseplant, Tomato & Veg, and Ericaceous — include a slow-release feed, so they work like a specialist multipurpose compost for their plant group, straight from the bag.
Why start from coir instead of a multipurpose bag?
| Peat-free multipurpose bag | Buffered coco coir brick | |
|---|---|---|
| Typical price per litre | 25p–45p (bagged, pre-wetted) | ~23p (£16.99 brick → 75 L) |
| What you carry home | 50 L of mostly water and air | 5 kg brick — expands with 20 L of water in 20–30 minutes |
| Consistency | Varies batch to batch (green waste) | Lab-tested every batch: pH 5.5–6.5, EC ≤0.5 mS/cm |
| Re-wetting after drying out | Variable | Rapid — coir re-wets readily |
| Feeding | Included for ~4–6 weeks | You control it — blend or feed |
| Peat | Check the label — "organic" does not mean peat-free | Zero, always |
How to choose a peat-free multipurpose compost (or skip it)
- Check "peat-free" is stated. Reduced-peat blends still exist; the word "organic" is not a guarantee.
- Look for the feed content. If the bag does not state added nutrients, treat it as a base medium — exactly like plain coir.
- Compare per litre, not per bag. Compressed coir looks dearer until you do the maths on expanded volume.
- For containers and seed trays, prioritise re-wetting and structure — the two things coir does best.
Frequently asked questions
Can coco coir replace multipurpose compost completely?
For containers, seed starting and hydroponics — yes, provided plants receive a complete feed, because coir itself holds almost no nutrients. For beds and borders, blend coir with compost rather than replacing soil outright.
Which is cheaper — a multipurpose bag or a coir brick?
Per usable litre, compressed coir usually wins: a £16.99 brick expands to around 75 L (~23p/L), while bagged peat-free multipurpose compost typically costs 25–45p/L once you compare like for like. You will need to add feed, which costs pennies per litre.
Is peat banned in multipurpose compost?
There is no statutory UK ban currently in force — a private members' bill was introduced in February 2026 but is not law. The shift is being driven by retailers and institutions: B&Q, Kew and the RHS have all moved peat-free, which is why shelves have changed.
Do your mixes count as multipurpose compost?
Our Houseplant, Tomato & Veg and Ericaceous mixes include a slow-release feed as well as buffered coir, so within their plant group they do the job of a specialist multipurpose compost. Our Seed, Cactus and Orchid mixes are deliberately low-feed or free-draining — designed for plants that dislike rich media.
Try the peat-free alternative
5 kg Buffered Coco Coir Brick — £16.99 (expands to 75 L, ~23p per litre) · 3-Pack 15 kg — £46.99 (225 L) · Ready-to-use plant-specific mixes
Not sure how much you need? Use the calculator.
Continue learning
- The Best Peat-Free Composts in the UK (2026) — our tested round-up
- Coir Compost: A Complete Guide — coir as a compost alternative in depth
- Coco Coir (Coco Peat): The Complete UK Guide — the full pillar guide