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Inveraray Castle and Arduaine Gardens spring into bloom as the Scottish Rhododendron Festival begins this month, offering ‘rhodo walks’ around 20 estates in Argyll and the Isles until May 31.
The festival, organised by Discover Scottish Gardens, aims to encourage locals and tourists ‘to enjoy the wonders of Scotland’s gardens during the rhododendron flowering period’, as swathes of bright yellows, purples, pinks and reads brighten up the dullest of days.
Visit Scotland explains: ‘The rhododendron is a huge family of around 1,000 species, from small mountain shrubs to magnificent tree-like specimens.
‘Rhododendrons require acidic soil to thrive and some of their natural habitats include the Himalayas, Japan and China. Luckily for us, most soil in Scotland is naturally acidic, making it a great place for these beautiful shrubs to flourish.’
The curator of Edinburgh’s Royal Botanic Garden, David Knott, said: ‘Rhododendrons make such a significant contribution and provide fantastic displays in many Scottish gardens. They range in height from large tree-like plants, to dwarf alpine shrubs, and depending on the weather there will be rhododendrons in flower from February right through to August. Many will have already begun to bloom in gardens across the country, despite the recent bad weather.’
However, when rhododendrons escape these beautiful gardens, controversy can follow. Last year Scottish ecologists working on the West Coast discovered native plants need a helping hand if they are to recover from the ‘invasive’ species.
A study in the Journal of Applied Ecology revealed that – even at sites cleared of rhododendron 30 years ago – much native flora has still not returned. As a result, rhododendron eradication programmes may need to be supplemented by reseeding for the original plant community to re-establish.
Working in the Atlantic oak woodlands of Argyll, Kintyre and Lochaber on Scotland’s west coast, researchers from the James Hutton Institute, the University of Aberdeen and Scottish Natural Heritage found that – even 30 years after rhododendron removal – the native understorey normally found in Atlantic oak woodlands had not recovered. Instead of dramatic displays of primroses, violets, wild garlic, ferns and grasses, only dense mats of mosses and liverworts had returned.
Lead author Dr Janet Maclean said: ‘Uninvaded Atlantic woodlands are often called the Celtic rainforest. With their gnarled, lichen-covered trees, rich carpets of moss and burns tumbling down rocky ravines, they look like something from Lord of the Rings.’ In spring, luxuriant carpets of bluebells cover the ground, interspersed with the fiddle-heads of the diverse fern species starting to emerge.
‘Sadly, rhododendron-invaded woodlands present a different vista, vast stands of this single species replacing all the diverse native flora as far as the eye can see. The forest floor becomes a dark, barren place devoid of life apart from the dense rhododendron stems barring the way in all directions,’ she says.
The paper added: ‘Since it was first imported in 1763 to brighten up our gardens, rhododendron has become one of Britain’s most damaging invasive species.
‘Rhododendron has spread throughout the UK, affecting around 827,000 hectares, and is particularly widespread across western Scotland and Snowdonia. Eradication programmes cost around £8.6 million a year and the results of this study show that – as well as removing rhododendron – land managers should also consider clearing mats of common mosses from the ground and reseeding with typical woodland grasses and flowering plants.’