TL;DR
Multipurpose Compost (MPC) is a modern, soilless, all-purpose mix designed for ease of use. John Innes 1, 2 and 3 are traditional, soil-based formulas graded by nutrient strength and tailored to plant growth stages.
Composition
Multipurpose Compost (MPC):
Peat-free or reduced-peat blends using wood fibre, coir, bark or green compost. Lightweight, easy to handle, and pathogen-free — but usually soilless and microbially inactive.
→ See FAQ: What is John Innes compost?
John Innes Mixes:
Based on the 1930s formula using sterilised loam, peat, and sharp sand, with balanced lime and fertiliser additions. The loam adds structure, buffering, and a little microbial life often missing from MPCs.
Nutrient Levels and Plant Stage
| Mix Type | Typical Use | Nutrient Level | Notes |
|---|---|---|---|
| John Innes No. 1 | Seedlings & young plants | Low | Gentle feeding for rooting |
| John Innes No. 2 | Potting-on & established plants | Medium | Balanced for steady growth |
| John Innes No. 3 | Mature plants & shrubs | High | Sustains long-term container growth |
| MPC | General all-rounder | Varies by brand | Fertilised for only 4–6 weeks typically |
Water and Structure
- John Innes: heavier, moisture-retentive, slower to dry — ideal for long-term pots.
- MPC: lighter, drains rapidly, and can become hydrophobic once dry.
Biological Activity
Because John Innes includes loam, it supports some microbial life and natural buffering. MPCs are typically microbially inactive, prioritising cleanliness and shelf-life.
→ More detail in: Biological Activity of Compost.
Cost & Convenience
MPC = light and cheap.
John Innes = heavier and steadier, but costlier per litre.
Which Should You Choose?
- For everyday potting and containers → choose Multipurpose Compost.
- For precision or long-term growing → use the relevant John Innes number.
Many gardeners blend the two: MPC for bulk lightness, John Innes for weight and nutrient buffering.
Official Formula Update — Peat-Free John Innes (2020 → Now)
Yes — the official John Innes formula has been modernised to remove peat.
The John Innes Manufacturers Association (JIMA) introduced peat-free versions around 2020–2021. Peat is now replaced by:
- Coir (coconut fibre)
- Fine bark or wood fibre
- Composted green waste
These maintain the original nutrient ratios and loam:sand proportions.
Note: The name “John Innes” isn’t trademark-protected — so not every brand follows JIMA guidance. Always check the bag for “peat-free” or “JIMA-approved formula.”
Visit the John Innes Manufacturers Association website
Summary
Multipurpose Compost = light, versatile, convenient.
John Innes = structured, soil-based, and nutrient-graded.
Both have value — choose based on plant stage, watering style, and whether you prefer living soil or inert substrate.
Disclaimer.
Brand names such as Westland, SylvaGrow, RocketGro, Dalefoot, Carbon Gold, and others mentioned on this site are registered trademarks of their respective owners. MultipurposeCompost.co.uk includes these examples for informational and comparative purposes only and does not claim endorsement, affiliation, or suitability for any specific use. Gardeners and buyers should always check current product specifications and manufacturer guidance before purchase or application.
