The annual RHS Chelsea Flower Show, held in London each May, is a showcase of the very best of British garden design, cultivation and, increasingly, sustainable practice.
But it is in the last category that Chelsea continues to flounder under its perfectly clipped veneer. This May’s show was supposed to be the last year plants grown in peat — the world’s most important terrestrial carbon preserve, storing more carbon per hectare than tropical rainforests — would take root. But in March the Royal Horticultural Society backpedalled on that pledge, announcing that nurseries will continue to be permitted to sell plants grown partially in peat at its flower shows until 2028.
Clare Matterson, the RHS’s new director-general, blamed “complex supply chains” and a “legislative black hole” for not being able to meet the target it set in 2021 to end peat use across its operations — including its gardens, nurseries, retail outlets and flower shows — by the end of this year.
The previous government had pledged to ban the sale of products containing peat for amateur gardening use in 2024, with a commercial ban to follow in 2026. But no such laws came into effect and, despite the availability of alternatives, peat still accounts for 43 per cent of the growing media used by professionals by volume, according to the Horticultural Trade Association. Peat remains present in show gardens, too: not one of the 39 show gardens in 2022 was free of it. “There are so few nurseries that grow for Chelsea that designers don’t have much flex,” says a former Chelsea show garden designer, speaking on condition of anonymity.
In recent years the RHS has sought to reframe gardening as an opportunity to improve the wellbeing of people and the planet. But that message looks like hot air as long as the industry continues to lean on a raw material whose removal contributes directly to global warming and wildlife habitat loss. Why can’t horticulture — a sector and a practice intrinsically linked to nature — end its reliance on peat? And as long as the stuff remains endemic in the supply chain, can anyone who buys plants have confidence that their gardens are good for the planet?
“It’s so disappointing they are changing this rule right when we need to be pressuring government,” says garden designer and RHS trial judge Jack Wallington, who accused the charity of bending to the interests of its corporate sponsors. “This isn’t gardening; it is out-of-control capitalism.”
Others were more diplomatic. “The RHS has been doing more than anybody to persuade the industry to go peat-free,” says Sally Nex, author and advocate for the Peat-free Partnership, an RHS partner charity. “The industry has not responded.”
Peatlands are carbon-rich wetlands whose acidic and waterlogged conditions prevent vast quantities of plant matter from decaying and thus releasing carbon dioxide. They also filter water pollutants and, because they act like a giant sponge, prevent flooding in surrounding areas. It takes 1,000 years to form just one metre of peat.
The UK’s three types of peatland (blanket bog, lowland raised bog, and fen) cover 3mn hectares; about 80 per cent are in a “degraded” condition, meaning that instead of sequestering carbon they emit around 20mn tonnes per year — around 4 per cent of the country’s total terrestrial greenhouse gas emissions, according to the UK Centre for Ecology and Hydrology. Of the lowland peat bogs (those mined by the horticulture industry), more than 96 per cent have been wiped out since 1850, much of it lost to forestry and agriculture, leaving just 10,000 hectares.
Restoring damaged peatlands and preserving the small intact stretches that remain is a critical part of the UK’s strategy to reach net zero emissions by 2050.
The industry’s love affair with peat began in the 1960s, when nurseries and garden centres started selling plants in cheap, transportable plastic containers en masse. Peat, which is clean, lightweight and holds moisture and added fertilisers well, was the perfect medium to house these young plants, which could be put in the soil year round. Prior to this, plants were mainly sold as bare roots to be planted in the ground when they were dormant in late autumn and winter.
But by the late 1980s it had become clear that these colourful displays had come at a cost. Author and environmentalist Jeremy Purseglove described the destruction wrought by a peat-mining operation at a low-lying peat bog in Landscape Design in 1989:
“The unforgettable spectacle which Hatfield Chase presents . . . is not so much its natural splendour as the ruin which man is inflicting upon it. Beyond [the peat works] extends 2,000 acres of totally stripped-out, black, gleaming peat; an area equivalent to that of a sizeable town. Machines, looming out on the moor like space-age dinosaurs, pick over the raised mire, systematically dismembering it until there is nothing left. Hatfield Chase took 3,000 years to evolve . . . Now, in perhaps 10 years or less, it will be gone, taken away bag by bag . . . for brief summer crops of tomatoes in our greenhouses, and to be scattered on people’s rockeries.”
The following year, 10 environmental non-profits including Friends of the Earth and WWF banded together to launch the Peatland Campaign with the aim of ending peat use in horticulture and preserving the remaining 4 per cent of peatlands. King Charles, then the Prince of Wales, threw his support behind peatland conservation; the RHS vowed to go peat-free across all its gardens. Research into alternatives commenced and by 1992, scientific trials showed that peat-free alternatives could, when applied properly, perform as well as peat-based products.
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But progress was achingly slow. Seven years after the campaign started, only 8 per cent of the growing media sold in the UK was peat-free. This was partly because so few ready-made mixes were on the market; what was there was very poor.
“All the compost makers rushed to bring out peat-free compost, and it was absolute shite,” recalls Mark Straver, co-founder of Hortus Loci, a nursery that has been peat-free for five years and is the biggest supplier of plants for show gardens at Chelsea (it is supplying seven this year, including gardens by Tom Massey and Nigel Dunnett). “It was fine for retail sales, but they couldn’t regulate the acidity and if you trialled 20,000 plants it looked appalling compared to peat. Over the years the products got better . . . We use seven or eight different [mixes] now and I wouldn’t notice any difference [from peat].
“I would urge everyone: just change,” he continues. “I was the worst offender for using peat for too long, because I had my fingers so badly burnt at the beginning. But now there’s no excuse. If the plants we grow get gold medals at Chelsea, how bad can it be?”
At Great Dixter Nursery in East Sussex, peat-free compost is art as well as science. “People come to us for two reasons: our plant knowledge and our potting compost,” says Michael Morphy, the nursery’s head.
It is one of the only nurseries that mixes its compost by hand, in wheelbarrows, with loam that it sources from its own meadows and sterilises in two well-worn machines the size of home kilns. That is then combined with Melcourt Sylvafibre (a wood fibre mix with a similar consistency to peat), bark, grit and a controlled-release fertiliser — Morphy says he and his team are always experimenting with the formula, sometimes adding crushed brick (“too porous”) or leaf mould (“better for aeration”).
The only reason this labour-intensive method is commercially viable is because Great Dixter is part of a charitable trust, Morphy says. The nursery has been peat-free since the late 2000s, “but we’re not perfect”, he’s quick to add.
He is often appalled by the inconsistency of bagged compost, which can be good one year and poor the next. (He recommends following the Gardening Which? guides to decide what to buy each year.) The risk of inconsistency is the main reason Dixter continues to mix its own, which is heavier and far grittier than that sold at garden centres.
Morphy stresses that growers can’t expect peat-free media to behave exactly like peat, and argues that the problems faced by the pro-peat lobby are primarily the result of mismanaged irrigation. “Different composts have different needs, and watering is the hardest thing to teach. Most things will die because of too much water or because they haven’t got any. It’s as simple as that.”
It’s not just boutique nurseries like Hortus Loci and Great Dixter that have quit peat successfully. Kernock Park Plants is a 100-person, family-run nursery and one of the UK’s largest suppliers of plug plants, producing 13mn per year. These tiny young plants, housed in just a few centimetres of compost, are sold via mail-order nurseries such as Crocus and Sarah Raven, whose customers can then plant them directly in their gardens, and on to “professional finishers”, who will grow the plugs into established plants before selling them on to supermarkets and garden centres (among other clients). “We always say that if there’s more than a few plants in your garden, we probably [propagated] it,” managing director Bruce Harnett says with a laugh.
This is the first year that Kernock Park Plants will operate entirely free of peat — the culmination of nine years of trial and error. Kernock began experimenting with peat-free media more than two decades ago, but didn’t get very far: “We killed a lot of plants, and thought right, that’s not happening.”
In 2011, the government warned that it would ban peat use in horticulture unless the industry “voluntarily” did so on its own by 2020 — which persuaded Kernock, in 2016, to try again. “We worked on improvements with our suppliers, and now we grow [all 1,200 varieties] of our plugs peat-free,” says Harnett.
Eliminating peat is not simple, particularly for a large commercial grower. Peat-free media is more expensive. Irrigation and feeding are also gauged for peat, and plant losses are inevitable while nurseries make the switch. Growing mixes must also be modified for different types of plants, as well as for seasons. It’s also hugely pervasive in the supply chain. Kernock had long been getting cuttings (ie young shoots) from plants grown in peat to produce new plants.
Originally, Harnett was concerned that swapping peat for peat-free media would be trading one environmental problem for another. Coir, for example, is made from coconut husks, a waste product largely imported from south-east Asia (though Catherine Dawson, senior associate at compost maker Melcourt, says the percentage in potting compost is small and the associated carbon is far lower than that of peat). But now “we’re sure we’re doing the right thing and developing the most environmentally sustainable media”, he says.
Not everyone is on board with peat-free. Critics of the proposed ban argue that the 1mn cubic tonnes of peat used for British horticulture each year is paltry relative to agriculture and forestry demands, and that the alternatives are inferior, more expensive, and require more water and fertiliser.
Some insist that 100 per cent peat-free cannot be done. Kenneth Cox is the managing director of Glendoick Garden Centre in Scotland, which specialises in rhododendrons, azaleas and other ericaceous — acid soil-loving — plants. He has been trialling peat-free composts for years with little success.
“The results were tolerable for the first three months,” he says of the most recent round of trials. “Then they began to die off. We lost 25 per cent [and] no plant was saleable.” It has proven even more difficult for propagation, he adds: “We cannot currently root rhododendrons and azaleas without the use of peat.” Although he acknowledges the high carbon footprint of peat, and has reduced the nursery’s use of it from 80 to 30 per cent, he is critical of the emissions associated with transporting and cleaning substitutes such as coir.
Ericaceous plants have proven more challenging to adapt to peat-free compost, acknowledges Alistair Griffiths, head of science at the RHS, though recent trials with those grown at Hillier Nursery in Hampshire, the UK’s largest grower of trees, have been “very promising”.
The RHS continues to ask the Labour government to pass the long-promised ban on peat with clear timelines and support packages to help provide clarity for the industry’s transition to peat free, he adds.
Griffiths has been working to transition away from peat since the 1990s, when he worked at the Eden Project in Cornwall growing 2,500 types of tropical plants without peat. He now oversees a team of 10 researchers, technicians and buyers helping the industry to transition to alternative media. Together they work with 10 commercial growers and 10 media producers on trials involving half a billion plants per year, and enable knowledge transfer to those still using peat. Griffiths says the RHS has invested £2.5mn and 150,000 hours of research into peat alternatives. He is so preoccupied with its success that, when we speak over the phone, he is examining the plug trials he is conducting in his own back garden.
Another of the “final challenges” is unpicking the UK horticultural industry’s supply chain. Sixty per cent of the plants sold in the country begin as peat plugs imported from mainland Europe, mainly the Netherlands and Germany, which are nurtured by professional finishers.
Griffiths has begun working with those plug suppliers, too. He says it’s a myth that the UK is the only country working to move away from peat, and that the plug producers he visited in mainland Europe last year have begun trials on alternative media. “The UK is about 7 to 10 per cent of the Netherlands market, if we [enact the ban], they will make the change.” Germany and Switzerland are also exploring potential peat bans as they work to reduce its use across the hobby and professional sectors.
“I am exhausted but we are going to keep pushing,” Griffiths says.
Until I began reporting this story, I had not realised how pervasive peat still is in horticulture. I only began gardening intensively three years ago, have never bought peat compost and would have told you, naively, that my garden was peat-free.
But a closer examination of the seven nurseries I give most of my business to reveals that only two — Great Dixter and Beth Chatto — are peat-free. And although my local garden centre stopped selling peat composts a few years ago, they still order plants from nurseries who use peat plugs and from suppliers who raise houseplants in peat. There is nothing on their plant labels to indicate what’s been grown peat-free.
“As a consumer it’s hard to know if something has peat in it,” says Wallington. “Consumers shouldn’t be shouldering this burden. They’ve been crying out for this [change] for years.”
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Since the late 1990s, successive governments have set targets for the horticulture industry to “voluntarily” transition away from peat, which have failed repeatedly by wide margins. And while protecting peatlands is in the new Labour government’s manifesto, it has not yet committed to proceeding with the previous government’s proposed ban. A spokesperson for the Department for Environment, Food & Rural Affairs tells the FT it is “examining potential next steps to ban the retail sale of horticultural peat and will set out further detail in due course”.
If there’s a larger lesson to be learnt from all of this, then, it’s that voluntary changes from a business sector — even when overwhelmingly endorsed by the public — can only go so far when it comes to tackling the thorny and complex issues surrounding climate change.
It can also delay progress in other areas. Peat is just one of many environmental problems horticulture has still to face. Few nurseries are organic, and sales of wildlife-harming pesticides, slug pellets and single-use plastic continue apace — some would argue because the decades-long debate on peat is still running. As Wallington says: “We need to move on.”
Lauren Indvik is the FT’s fashion editor
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