Most composts available in supermarkets or garden centres are made of a high proportion of peat – even if they don’t state it. But why does that matter?
Peat and peat-free compost
Multi-purpose compost is usually made up of between 70% and 100% peat. Peat is decayed vegetation and organic matter, which is created by sphagnum mosses growing in bogs. Peat is commonly found in compost as it has a great ability to hold water and nutrients, helping your flowers and vegetables thrive. It has been used by gardeners since the mid 20th century and is usually mixed with sand and loam (sand, silt and clay mixture).
Peat-free composts contain mixtures of organic (e.g. composted bark, green waste – food waste, coconut fibre waste, straw waste, homemade) and inorganic material (e.g. grit, sand). Peat-free composts are often thought of as being inferior to peat composts because a lot of early peat-free composts left gardeners infuriated with poor results. However, the quality of peat-free composts has massively improved in recent years, with gardening organisations now promoting their use.
Why is peat based compost bad for the environment?
Our demand for peat is resulting in the destruction of peat bogs, which are now one of the UK’s most threatened habitats. Peat bogs/ peatlands might not sound like appealing environments, but they provide a lot of benefits to the world, including providing homes to a full range of plants, insects and birds, and acting as a natural flood defence by soaking up vast quantities of water.
Most significantly, peat bogs act as one of the world’s largest CO2 stores – and with humans producing more CO2 than ever, we need to protect and enhance these sinks, so that more CO2 can be stored. The UK’s peat bogs hold more than 3 times the CO2 of the country’s forests. Destroying peat bogs for garden compost therefore contributes towards climate change, with around 39 tonnes of CO2 released into the atmosphere per hectare of lowland peat that is destroyed each year. Many academic studies on peat carbon storage can be found online.
Peat is also a limited resource – it expands very slowly (by about 1mm a year), so there are not unlimited supplies. Commercial extractors of peat typically remove 22cm of peat a year (e.g. over a century’s accumulation). As amateur gardeners use around 66% of the total peat consumed in the UK, it’s important we all make the switch away from it.
Will my plants grow without peat? Why are people still using peat?
The main benefits of peat compost are that it’s great for holding nutrients and water. However, peat-free composts can do this too. Drainage may not be as good as in peat composts, but the addition of grit to peat-free compost can improve this. Plant food can also be used to increase the nutrients in the compost.
Gardening organisations agree that peat should be phased out, so they’re obviously not concerned about the viability of plant life without it. Many peat-free composts give excellent results according to the Royal Horticultural Society. The standards of peat-free composts keep improving, and they’re now often considered just as good or even better than peat composts.
It’s clear we need to move away from peat-based composts. When buying compost, most contain peat without you even realising it. It’s important to look out for composts (and potted-plants) that explicitly state that they are “peat-free”. These composts might be a bit more expensive, but they have clear benefits over peat based composts.
From 2024, the UK government are banning the sale of peat based composts, so we might as well make the switch now. Some of the sources below can help you know where is best to buy peat-free composts and how to get the most benefits out of them.
RHS – Peat-free growing media – https://www.rhs.org.uk/advice/profile?pid=441
BBC – The ethics of using peat – http://www.bbc.co.uk/gardening/today_in_your_garden/ethical_peat.shtml
The Garden Superstore – Peat vs peat free – choose the right potting compost – https://www.thegardensuperstore.co.uk/advice-and-inspiration/peat-vs-peat-free-choose-the-right-potting-compost
Which – Should I buy peat-free compost? – https://www.which.co.uk/reviews/compost/article/should-i-buy-peat-free-compost-agoem9L4NI04
SAGA – Peat-free compost: why use it, and which brands? – https://www.saga.co.uk/magazine/home-garden/gardening/advice-tips/soil-improvement/peat-free-compost
Jack Wallington Garden Design – Does peat free compost work? – https://www.jackwallington.com/does-peat-free-compost-work/
Which – Peat compost set to be banned – which peat-free composts are any good? – https://www.which.co.uk/news/2021/05/peat-compost-set-to-be-banned-which-peat-free-composts-are-any-good/
The Guardian – Sales of peat compost to gardeners to be banned from 2024 – https://www.theguardian.com/environment/2021/may/18/sales-of-peat-compost-to-gardeners-to-be-banned-from-2024
Sunday Gardener – Peat moss: benefits and disadvantages – https://www.sundaygardener.net/peat-moss-benefits-and-disadvantages/
The Guardian – Tips for a peat-free garden – https://www.theguardian.com/lifeandstyle/gardening-blog/2010/feb/23/peat-free-compost