Peat-Free Gardening: Why and How?

Peatlands are incredible ecosystems that play a vital role in storing carbon. They hold almost a third of the soil carbon even though they only cover around 3% of the planet’s land surface.^[1] Scotland is rich in these unique landscapes but they are under great threat through peat extraction which not only destroys them but also greatly contributes to climate change.

Today’s blog post explores how the horticulture industry is playing a major role in the destruction of the peatlands. It will look at what we can do to protect these magnificent ecosystems and how we can still garden successfully without using peat.

Flanders Moss from Kippen, Stirling Council area. Largest raised bog in Europe.

(Photo by Rosser1954. This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International licence.)

What are Peatlands and Why are They Important?

Peatlands are wetlands like bogs, swamps, fens and moors. Peat is the organic surface layer of these landscapes. It is made up of partially decomposed plant material from over 12,000 years ago. Peatlands are waterlogged, acidic and lack oxygen and nutrients. As a result the plant material does not fully decompose. Organic material keeps accumulating at a faster rate than it decomposes and the peat layer develops.

Plants that decompose under oxygen turn into carbon dioxide but plant matter in peatlands turns into carbon. This is why peatlands are ‘carbon sinks‘. They are storing the carbon that would usually be released as greenhouse gases into the air so the peatlands help reduce global warming.

Apart from this, peatlands can hold large amounts of water which can reduce the risk of flooding. A lot of the Scottish drinking water comes from peatlands and many of Scotland’s salmon rivers depend on peaty catchments.

The peatlands are home to a unique range of plants. These include sundews (Drosera sp.) which are carnivorous plants that trap insects with hairs covered in sticky dew and Sphagnum moss. Many rare animal species can also be found in peatlands such as dragonflies, lizards and birds like golden plovers and hen harriers.

Peatlands cover around 10% of the UK land area with two thirds of them located in Scotland.^[2] There are four types of peatland present in the UK. These are blanket bogs, raised bogs, fens and bog woodland.

Blanket bogs are usually found in the uplands, especially in the West Highlands and Western and Northern Isles of Scotland where they cover extensive areas as mantles of peat. Blanket bogs typically only receive water through rainfall. They are nutrient-poor and acidic. Blanket bogs are globally rare but the UK contains 13% of the world’s blanket bogs.^[3]

Raised bogs are lowland bogs that consist of mounts of peat that are higher than the surrounding land. They are also nutrient-poor and acidic and support similar species to the blanket bogs. Large areas of raised bogs have been lost to agriculture, horticulture and forestry.

Fens are diverse in the type of environment they can support, ranging from bog-type vegetation to richer soils that can support sedges and reeds. In addition to rainfall, fens receive underground water.

Bog woodlands are wooded areas with underlying bog vegetation. The main tree species is usually pine but birches and willows can also be present. The vegetation underneath the trees resembles that of open bogs. They are the rarest form of peatland in Scotland and usually the most wild and un-managed as they are difficult to access.

Peat in Horticulture

Peat has many qualities that make it ideal for composts and as a growing medium which is why it has been a staple ingredient of horticultural compost for many years.

Peat can hold moisture of up to 20 times its own dry weight which means a growing medium that includes peat will not dry out easily. At the same time plants are unlikely to become waterlogged because peat has air pockets that allow for drainage and for oxygen to reach the plant roots. Peat is also free from weeds and pathogens as a result of forming in the acidic, sterile conditions of the bogs. Peat-based growing media are usually of consistent quality because there is no microbial activity that could change and affect the quality.

While peat holds nutrients well from fertilisers it does not have many natural nutrients itself that would benefit soil life and plant growth.

According to Defra (Department for Environment, Food and Rural Affairs) 70% of peat sold in the UK in 2023 was in the retail gardening sector.^[4]

Detrimental effects of peat extraction

Peat for gardening is mainly extracted from raised bogs. The mechanised removal of peat strips away the living layer of the bog to access the partially decomposed matter underneath it. This exposes large quantities of peat to oxidation. The stored carbon is then released as carbon dioxide into the atmosphere. This increases the greenhouse effect and thereby directly contributes to climate change. The process also damages and destroys the bogs and their unique flora and fauna.

As part of the extraction the bogs are drained which not only causes oxidation of the carbon but also drastically lowers the water table. This does not only affect the bog that peat has been taken from but can also cause neighbouring areas to become degraded. When the extracted peat is spread onto a garden or field even more carbon is released as carbon dioxide.

Peatlands take thousands of years to form and only grow back by about 10 cm every 100 years. Mechanical removal of peat allows it to strip away as much as 22 cm of depth in one go^[5] – that’s 22,000 years worth of peat growing! Peat extraction means that peatlands are depleted faster than they can replenish which makes harvesting peat unsustainable.

Peat Ban

Peat-free composts have been on the UK market for a long time but until recently were a niche product and not always available in garden centres. In 2022 the UK government announced a ban on the sale of peat and peat-containing products in the retail horticultural sector by 2024 with a full ban including commercial use to follow by 2030.^[6] This step recognises the detrimental effects of pest extraction and aligns with global efforts to address climate change.

Regrettably the government does not appear to be making this a priority as the ban keeps being delayed.^[7] As of now the retail sale of peat-based composts and soil improvers is still legal. Banning peat-based products for private use by the end of this year would put the UK ahead of the EU where a ban is only planned for 2026.

As a result of peat extraction peatlands currently release more carbon than they store.  They could once again become the incredible carbon stores that they used to be if intact peatlands were protected better. Drained peatlands could at least be partially restored through rewetting. This would also protect their unique flora and fauna and help alleviate the effects of flooding.

As a result of the announced ban, growing media companies are increasingly switching to offering peat-free products as part of their retail range. It is encouraging to see that peat-free composts are now the standard option in many garden centres.

Gardening retailers and conservation charities are making their own peat-free pledges. For example The National Trust says that they no longer use peat for mulching or soil improvement and all the plants they grow, buy and sell are potted in peat-free compost.^[8] The Royal Horticultural Society claims that they are 98% peat-free and are striving to be 100% peat-free by the end of 2025.^[9] B&Q has been selling exclusively peat-free compost since 2023^[10] and Caledonian Horticulture has always been proudly peat-free.

Challenges of Shifting to Peat-Free

As discussed above, the switch to peat-free composts is overdue and essential. However, it does not come without its hurdles.

Peat-free composts and growing media have come a long way and there is now a large variety of high-quality, renewable ingredients used in their production but a lot of these materials come with their own ecological considerations.

Alternatives to peat used in composts and growing media usually included a mix of organic materials (such as composted green waste, bark, wood fibre, sheeps wool and coir) and inorganic ones (rock wool, perlite, sharp sand and grit).

Coir is made from coconut husks. The extraction process involves the use of a lot of water and often chemical treatment. It usually needs to be imported with transport contributing to carbon emissions and it may harbour pathogenic fungi if of poor quality. Composted green waste processing can also be resource-intensive. Bark and wood-fibre are a forestry industry by-product and if not sourced from sustainably managed woods may contribute to deforestation. However, unlike peat, all of these materials are waste or by-products which gives them a clear ecological advantage over peat.

Peat-free growing media can vary greatly. A good quality peat-free compost will match the properties of peat. A mix of coarse and fine particles creates a compost that can hold moisture and air in the same way as peat. Materials such as coir and sheeps wool have great moisture-retention capabilities whereas wood-based mixes have similar draining properties to peat and low PH levels.

Unlike peat, most peat-free alternatives are not sterile. This can be both an advantage and a disadvantage. Healthy microorganisms present in the compost can greatly increase the quality of the soil and thereby improve the health of the plants growing in it. On the other hand, a low-quality peat-free compost may harbour pests and diseases.

Peat-free alternatives may not hold nutrients as well as peat. This means gardeners may need to add more fertilisers to them. If they use mineral fertilisers then they are using products that are energy-intensive to produce and originate from non-renewable resources such as fossil fuels. Often their extraction causes further problems such as habitat disruption and water pollution through run-off. Excessive use of fertilisers can degrade the soil and contaminate the ground in the garden and beyond.

How to Make a Smooth Transition to Peat-Free

The switch to peat-free has to involve not just the purchase of peat-free composts but needs to consider and implement overall sustainable gardening practices in order to be successful.

Choose peat-free compost from materials that are local or certified as sustainable to avoid transport emissions and support sustainable practices. Instead of mineral fertilisers use organic fertilisers such as manure or compost to enrich the soil, improve its structure and promote microbial activity. Caledonian Horticulture’s Kelpie Compost is a great choice for a locally produced compost with added nutrients. If possible make your own garden compost. This way you not only reduce the need for mineral fertilisers but also cut carbon emissions from transport to zero. Consider incorporating sustainable gardening practices such as crop rotation and mulching (see my previous post on mulching). These can improve soil health and thereby drastically reduce the need for fertilisers. It’s all about creating healthy soil to support healthy plants.

About the author: Sarah Gerhardt is a gardener, linguist and punk musician based in Edinburgh. She was head gardener at the Dean Gardens, Edinburgh for 9 years and runs her own gardening business Gerhardt’s Garden Service. Find out more via her Linktree: https://linktr.ee/gerhardtsgardenservice