There was King Charles and David Beckham as well as a nocturnal garden to support bats and a Viking-themed allotment full of edible plants in pots. The Royal Horticultural Society’s Chelsea flower show, which ends on Saturday, was as lovely and celebrity-glittered as ever, most agreed.

But dig a little deeper, say critics on the conservative wing of the RHS – including one spectacularly outspoken former contributor – and not everything is necessarily smelling of roses.

There has been a cashflow problem and, depending on whom you speak to, the root cause might be global events, financial losses due to A3/M25 roadworks blocking visits to RHS Garden Wisley or, in the mind of some, “wokery” and a lack of adherence to the traditional ways of doing things.

The RHS’s latest accounts filed with the Charity Commission reveal it recorded a net loss of £8.1m in the year ending January 2025 – double its losses of the previous year – raising concerns that financial pressures might grow like Japanese knotweed.

The RHS said unpublished financial accounts for the last financial year were much healthier. “With the well-documented impact of the M25/A3 behind us, last year the RHS grew its income by 7% and achieved a cash profit of £4.8m, whilst still investing £83m in our charitable work, and this April we enjoyed record garden visits and membership sign-ups,” it said.

But those concerned about the RHS’s future have been pointing to the need for the Chelsea flower show to find new charity sponsors after a mystery philanthropic couple, who have spent more than £23m on the show, ended their support this year. Meanwhile, the Newt, the luxury hotel in Somerset which was previously a longstanding sponsor, launched its own garden show this year, with the offer of free-entry to under 16s (there is no discounted ticket for children at Chelsea).

It is against this backdrop that the RHS has faced a conservative backlash, with critics pointing to comments from its treasurer, who had noted that the financial difficulties might be exacerbated by a transition to ensuring its shops are peat-free, a move made this January in recognition of the huge environmental damage caused by peat extraction.

Among those who believe the RHS has wandered up the wrong garden path is Tim Penrose, an award-winning RHS exhibitor whose Dorset firm, Bowden Hostas, once held a royal warrant with the then Prince Charles.

Penrose was blocked from exhibiting this year, he said, because he had failed to attend “anti-peat” seminars. He turned up anyway in a Superman suit claiming that only the fictional superhero could save the RHS now. Penrose said he had since been give a lifetime ban for his protest.

“In my application I agreed to adhere to their rules,” he said. “So I was very upset and astonished when they turned me down on the anti-peat issue, writing to me saying they would not be able to ‘give me space’ because I was not ‘committed’ to anti-peat policy and that I hadn’t attended any of their anti-peat seminars.

“They just don’t like me speaking out. There are others who agree with me about the way things are going, but everyone is too scared for fear of being excluded … There is unbelievable snootiness from staff who behave like school teachers … The thing is, you go too woke, you could go broke.”

The RHS declined to comment on Penrose’s statements but in recent years it has also been criticised for its lack of urgency in banning the use of peat.

Among those who have long championed the peat prohibition is the TV gardener Monty Don who has described gardeners who use the product in their garden as “lazy and irresponsible”. The extraction of the partially decayed organic matter is said to destroy unique ecosystems and accelerate climate change. The government had pledged to ban its sale but has yet to enact the legislation.

Such a ban involves extra costs for some nurseries and the sentiments voiced by Penrose have been echoed on the RHS’s social media channels, where there was further upset voiced about a garden that featured a parked Range Rover. The car manufacturer was a new sponsor this year.

One wrote: “Nurseries who have supported the RHS for years are being forced out because their plants cannot be grown in peat-free compost, especially carnivorous plants. And the RHS flagship event has a lithium mine on a driveway as a main focus, and AI-designed gardens.”

A second added: “RHS will do anything for a quick buck these days!!!”, while a third posted: “I can’t believe the RHS think this kind of promotion of a brand is a great idea for the future of the flower show … selling your soul to the corporate elite isn’t what horticulture is about.”

An RHS spokesperson said they were confident about the future. “RHS Chelsea is thriving and there is high interest from sponsors to do gardens in 2027,” they said. “The vast majority of nurseries are with us as we transition to peat free for the planet.”