More Than 33% of UK Compost Contains Climate-Warming Peat, Study Finds

Compost is generally seen as a positive thing for the environment, but it turns out that everything depends upon what that compost contains. 

In the UK, more than a third of compost sold in 2021 was peat-based, and this is a problem for the climate. 

“Peatlands are the world’s largest carbon store and provide valuable ecosystems for wildlife as well as important water services,” Royal Horticultural Society director of science and collections professor Alistair Griffiths told The Guardian. 

Peatlands are a type of wetland that are formed when plants decompose slowly in standing water, eventually creating peat. This is an extremely carbon-rich substance. In fact, peatlands, which cover around three percent of the Earth’s surface, sequester 550 gigatonnes of carbon, more even than forests.

However, when peat is harvested for compost or other purposes, it releases carbon dioxide into the atmosphere and contributes to the climate crisis. For example, in the UK 87 percent of peatlands are degraded and they emit 10 million tonnes (approximately 11 million U.S. tons) of carbon dioxide every year, according to The Guardian. 

Because of this, both private and public actors in the UK government are taking steps to reduce the use of peat for gardening. 

Major retailer Tesco announced it would be the first to eliminate peat from its British-grown bedding plants, The Independent reported Thursday. It said it would cut peat use by 95 percent on Monday and phase it out entirely by 2023. This will cut Tesco’s peat use by almost 9,000 cubic meters (approximately 317,832 cubic feet) a year and the annual carbon-dioxide emissions of its plant products by 75 percent, or 1,200 tonnes (approximately 1,323 U.S. tons). 

“[This is] a major step forward in delivering a more sustainable plant range to benefit the planet,” Tesco horticulture category buying manager Alex Edwards said, as The Independent reported. 

Other retailers including Dobbies, the Co-op and B&Q have also announced peat bans, according to The Guardian. 

Meanwhile, the government is consulting on the question of banning all peat sales to gardeners by 2024. The Horticultural Trades Association (HTA) argues against this, and submitted 2021 yearly peat sales to the government in response to the consultation.

The HTA figures revealed that nearly 5 million cubic meters (approximately 177 million cubic feet) of peat were sold in the UK in 2021. Thirty percent of the compost bought by gardeners was peat, but more than half the compost bought by horticultural businesses was peat. In total, peat made up 35 percent of sales. This was a 41 percent decrease from 2020, and HTA said that the industry is moving on its own without the need for a ban. 

“To remove peat from horticulture is not a question of if, it is entirely a question of when,” HTA wrote in response to the government consultation. “The taskforce in 2021 committed to end the sector’s use of peat, pledging to remove it from the retail market as early as 2025 and no later than the end 2028. For professional horticulture, the range is between 2028 and 2030.”

However, the government had previously hoped that garden centers would voluntarily stop selling peat by 2020, and that did not materialize, according to The Conversation. 

Dianna Kopansky of the Global Peatlands Initiative at UN Environment supported the idea of a 2024 retail ban, but thought the government should take additional action.

“Further action is needed to reduce the 1.7 million cubic metres of peat sold annually in the UK,” Kopansky said, as The Guardian reported. 

Research has found that composts containing bark, wood and coconut fiber can be as effective as peat, according to The Conversation.