TL;DR
Most compost bags say eco-friendly or planet-kind — but what’s really inside matters. This page explains what “carbon footprint” means, why some composts are better for the climate than others, and how to spot the genuine green choices.
Why Carbon Footprints Matter
Switching to peat-free compost is a good start, but not all peat-free mixes are equal. Some are made locally from recycled green waste; others use imported materials like coir (coconut fibre) that travel halfway round the world. Both can grow great plants — but their carbon stories are very different.
What a Carbon Footprint Really Is
Think of it as a tally of energy use and emissions from start to finish — from collecting the raw ingredients, through composting or drying, to packing, transport and finally what happens in your garden.
Because different studies measure slightly different things, any figures you see are best treated as rough guides, not hard facts. The key idea is simple: shorter journeys, lower energy use, and recycled ingredients usually mean a smaller footprint.
How the Main Ingredients Compare
- Coir – made from coconut husks and imported from Asia. Bulk shipping is efficient, but drying and distance add up.
- Wood fibre – made in the UK from waste timber; processing uses energy, yet transport miles are short.
- PAS100 green-waste compost – created from local garden clippings; often counted as carbon-negative because it diverts waste from landfill.
- Digestate blends – based on by-products from anaerobic digestion; nutrient-rich but tricky to manage well.
- DIY or home compost – the winner for low footprint; little energy, no transport.
Wood-Rich Composts: The Hidden Variable
Even certified composts can look and behave quite differently. PAS100 sets standards for safety and stability, but it doesn’t guarantee a fine, fully broken-down product. Typical batches are screened to 15–25 mm, which means they often contain 25–50% small wood chips left over from the bulking stage.
- act as slow-release carbon — great for soil structure but poor for feeding plants,
- can tie up nitrogen while they finish breaking down, and
- may dry out faster if the chip content is high.
So “peat-free” doesn’t always mean “plant-ready.” Texture and maturity count too.
How to Read the Labels
- Peat-free or 100% peat-free (this will soon be law)
- PAS100 or similar certification
- A note about where it’s made — local beats imported
- Any sign of carbon or sustainability data (QR link, LCA info)
- Avoid vague words like eco, green, or planet-friendly with no detail behind them
See also Carbon Standards and Labelling – Buying Guide for help decoding sustainability logos.
How This Affects Our Review Scores
When we review composts, we don’t stop at plant performance. Our scoring looks at:
- How transparent the maker is about carbon data,
- Whether ingredients are local and recycled, and
- Evidence of genuine improvement, such as renewable energy use or biochar addition.
A mix that’s good for your plants and your soil life is one thing — a mix that’s good for the planet too is even better.
Want the Science?
If you’d like to see how the carbon numbers are worked out, visit our sister site:
👉 Carbon Footprints of Compost – Technical Comparison
Summary
- Not all peat-free composts are equal.
- Local, PAS-certified, and wood-balanced mixes tend to have the lowest footprints.
- Lots of visible wood = slow-release carbon, not instant plant food.
- Honest, transparent labels beat clever green words every time.
Choose compost that supports your plants, your soil, and the wider environment.
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.
