FOR years it has been one of the most colourful but destructive pests damaging Scotland’s native woodlands and gardens.
Now rhododendron is being turned into a green fuel in a bid to create some benefit from the endless task of burning the shrub to control its spread.
The National Trust for Scotland is buying kilns to produce charcoal for barbecues from the vast quantities of rhododendron blighting its properties.
Rhododendron is a major problem at eight NTS countryside sites after spreading from neighbouring land or from being planted in NTS gardens before its destructive impact was fully understood.
Five NTS sites across the country will start producing the fuel commercially next spring, including Brodick Castle and Country Park on Arran, while mobile kilns are due to be used at additional sites as the project develops. The four other properties taking part are Culzean country park in Ayrshire, Arduaine garden in Argyll, Inverewe estate in the Highlands and the Killicrankie gorge in Perthshire.
Clearing the dense shrub takes months and has cost the NTS millions of pounds, with £500,000 being spent at Brodick alone over the past two decades clearing rhododendrons on 24 hectares.
Commercial sale of the fuel in NTS shops will not generate enough income to turn the vast cost of getting rid of the shrub into profit, but staff said it would help reduce waste and cut costs.
Alasdair Eckersall, NTS property manager at Ben Lomond, who will lead the project, explained the inspiration behind it.
He said: “A colleague, who has since left, first started making charcoal from rhododendrons here and selling it to campers on Loch Lomond about five or six years ago.
“It’s a relatively straightforward thing to do. We make about 600kg a year here, which isn’t a huge amount, but we sell to local folk as well as visitors for around £8 per 4kg bag and we have now run out of rhododendrons in our area.
“Making the charcoal is not seen as something that can generate great profits – although it can pay for itself financially – it is more about making good use out of a resource that would otherwise be burnt simply to get rid of it, with it not doing anything useful while being burnt.”
He added: “We certainly won’t be flooding the market with NTS charcoal, but as people get to grips with it more, it will hopefully become a staple part of how the trust processes waste wood from invasive clearance and other work.”
Rhododendron ponticum was first introduced to Scotland from south-west Spain in 1763. Within a century it was found in the wild and it has spread widely during the 20th century.
In the past 50 years, growth has accelerated rapidly, and while some experts believe it has stabilised overall, others warn that the species is still expanding “aggressively”.
The dense invasive shrub, which can reach five metres in height, has taken over Scotland’s key oak woodlands, forcing out native plants, including bluebells. In the past few years clearing has increased to help prevent the spread of Phytophthora ramorum, a fungal disease which has jumped from rhododendrons to larch forcing forestry managers to fell thousands of trees.
The NTS estimates that it takes one person about three days to clear a 10m square area of rhododendron, including cutting the plant back, stacking up larger pieces for logs or charcoal and burning the smaller branches.
It would take another day to make charcoal from an area of that size, which would be expected to produce between 30kg and 50kg of fuel.
Only about 5 per cent of charcoal used in Britain is produced in the country, with hundreds of thousands of tonnes imported from overseas, often from unsustainable sources.
WWF Scotland director, Dr Richard Dixon, welcomed the initiative. He said: “I think it’s pretty pioneering and smart. I haven’t heard of anything like this being done with rhododendrons before.
“They are obviously a big problem in places where we don’t want them to be and it makes sense to try to turn that into a positive. Most charcoal that we buy here comes from overseas, and although some is Forestry Stewardship Council certified [as being sustainable], it’s far better for people to buy something they know has been produced locally.”
Gardening chain Dobbies, which currently imports all its barbecue charcoal, expressed interest in the scheme.
Richard Jardine, Dobbies sustainability manager, said: “We’re very intrigued about barbecue charcoal made from rhododendrons, it sounds like a great idea and we’d love to find out more.
“Gardeners tend to be more environmentally aware so I’m sure our customers would love to see a unique, home-made product like this on the shelves. We’d certainly be interested in helping support a move towards a locally sourced charcoal industry.”