Upgrade of Edinburgh's botanic garden facing cuts and delays

However a new report by the public spending watchdog Audit Scotland says the projected cost is now almost £100m, forcing the RBGE to look at scaling back and slowing down the scheme.

One option is to lose the most stunning element, a new eye-shaped glasshouse due to be built alongside the two existing glasshouses, which are being extensively renovated.

Kari Coghill, director of enterprise and communication at RBGE, said there had been issues with the project’s supply chain, with the cost of construction materials rising.

She told The Herald: “I think we have to be entirely pragmatic about this. Costs have gone up hugely. 

"We may just not be able to do everything we had hoped to do.”

Due to take seven years to build, the Biomes are one of the biggest projects in RBGE’s 350-year history, involving the decant of 20,000 plants.

Two crumbling A-listed Victorian Palm Houses at the heart of the Inverleith site will be restored, as well as the neighbouring 128-metre long modernist glasshouses built in 1967.

While the nearby research glasshouses, which are not normally noticed by the public, will be upgraded and - if the money is there - a new glasshouse created in front of them.

There will also be a new eco-friendly energy centre, cutting the carbon footprint of the glasshouses by 12 per cent, and a plant health suite to replace the existing nursery facilities.

The existing glasshouses are critical to the RBGE’s indoor living collection of around 4,000 species of plants, including the Amorphophallus titanum “corpse-flower” from Sumatra, which produces a flower nine feet tall that opens for only a few days.

The RBGE’s aim is to create a spectacular experience for its million visitors a year, and maintain its status as a world-leading centre for plant science, education and conservation.

However the plans are costly, and as the new annual audit report on the RBGE’s finances states, inflation has raised those costs "significantly". 

The Scottish Government pledged to pay £58m of the original £70m cost, but the bill is now estimated at £97m, leaving a funding gap of £39m.

So far only £5m has been covered by grants from the National Heritage Lottery Fund and other bodies. 

The RBGE is now hoping to attract funding from institutions and philanthropists overseas, with Regius Keeper Simon Milne currently in the United States meeting potential donors.

It is also looking to boost its revenue by hosting more corporate events, weddings, and monetising its scientific expertise through consultancy work. 

Ms Coghill said restoration of the heritage glasshouses would be vital, but other elements could be delayed or lost.

She said: “I think we’re going to have to look at everything, to be honest.

“We will need to look at everything from stretching out the programme to looking at losing bits of the project, potentially. The vision remains the same, and the masterplan is the same.

“But whether that now happens over a much longer period of time, or whether we pull the project back to the key elements we need [is unclear].”

Asked about the dramatic new glasshouse proposed for the site, Ms Coghill said it was "more likely to come at the end of the programme”, allowing it to be delayed or cut if necessary.

While the existing glasshouses were “the essential elements, we may have to lose the nice-to-have bits”, she said. 

Scottish Liberal Democrat leader Alex Cole-Hamilton, an Edinburgh MSP, said:"The Botanic Gardens and it's collection is a treasure of international significance.

"With a funding shortfall becoming apparent, it is time for the Scottish Government to get round the table and thrash out a deal that preserves the Edinburgh Biomes for future generations to explore and enjoy.

"Preserving biodiversity and understanding the complex processes that underpin our planet is only going to get more significant as the climate crisis escalates. I hope that the Edinburgh Biomes can play their part in this process."

A Scottish Government spokesperson said the Biomes was "a significant infrastructure project which promises to create new green jobs and contribute to emissions reduction while enhancing the Botanics’ significant global reputation", as well as helping the local economy.

“We are aware of the cost pressures being felt by the project – the result of rising costs being mirrored in projects across the UK and beyond. 

"In addition to standing firm on our commitment to contribute £58m to the project, we have been actively discussing the situation with the RGBE and will continue to help it explore additional funding streams to ensure the project’s successful conclusion.”