The Benmore Fernery

Mary Gibby


  Interior of the restored fernery lush with new planting
  (Photo: Mary Gibby; RBGE)

The Benmore fernery is a unique building in a remarkable setting. It occupies a remote site in Benmore Botanic Garden, Argyll. Nestled against the steep contour of a south west facing hillside, the fernery incorporates a cliff on its eastern side as an integral part of the structure. It was constructed in the early 1870s at the height of the Victorian fern craze, but went into decline in the early 20th century and lay derelict for nearly 100 years.

Ferneries are part of a strong tradition in Britain, one that reached its height in the second half of the 19th century when the country was gripped by ‘pteridomania’: the fern craze. It was Charles Kingsley, clergyman, naturalist and later author of The Water Babies, who coined the term pteridomania in 1855 to describe the fascination for ferns that was gripping the nation. It was manifested not only in the cultivation of ferns but in ‘fern ramblings’ and in a host of activities involving the identification, collection and exchange of fern species. The craze encompassed both British and exotic varieties, and it involved an impressive array of associated structures and paraphernalia.

Pteridomania was sustained by the publication of a wide range of literature, from short guide books to lavishly illustrated volumes of paintings and exquisite nature prints. Evidence of the passion for ferns remains with us in the form of the decorative fernware that made its first significant appearance at the 1862 International Exhibition in London in the form of fern-decorated pottery by Wedgwood and Dudson, etched fern glassware and fern-decorated wooden ‘Mauchline ware’. The Coalbrookdale Company of Shropshire produced decorative cast ironware in fern-like designs, including a range of cast iron garden seats. Unfurling fern fronds embellished grave stones and ornamental garden stonework. The decorated urns at Dawyck Botanic Garden, for example, are encircled by fronds of the hart’s-tongue fern and date from the 1840s.

There was a tremendous enthusiasm for cultivating ferns in ornamental Wardian cases (miniature glasshouses), fern gardens and, of course, ferneries like Joseph Paxton’s magnificent Tatton Park fernery in Cheshire and Kibble Palace, now gracing Glasgow Botanic Garden but first erected at Coulport, Loch Long.

Unfortunately, the passion for fern growing was accompanied by an obsession with collecting them from the wild, especially rare species. The populations of oblong woodsia (Woodsia ilvensis) that grew in the hills near Moffat in Dumfries and Galloway were devastated by collectors following the completion of the Carlisle-to-Edinburgh railway line over nearby Beattock summit in 1848. As the craze continued even the more common species suffered. John Hutton Balfour, Regius Keeper at the Royal Botanic Garden Edinburgh (RBGE), reported in 1870 that:

The ferns in Arran are gathered in vast numbers, and nearly all the accessible specimens of the rarer species are taken away… we saw boys and women carrying large quantities of ferns taken up by the roots with a view of making a profit by the sale of them.


The Benmore fernery was constructed for James Duncan, a wealthy sugar refiner. He had purchased the Benmore Estate on the Cowal Peninsula in 1870. During the 1870s he made many changes, with additions to the main house, the walled garden and the stable block. He also planted over six million trees, mainly conifers, across the estate. Adjacent to the house he built a large picture gallery for his extensive art collection which included contemporary works by the French impressionists, and an experimental sugar refinery.

Duncan’s heated fernery was at some distance from the other buildings in an area that had been recently planted with conifers. His picture gallery, sugar refinery and fernery have been described recently by architect Michael Thornley as ‘uncompromising buildings... allied more closely to industrial rather than domestic styles of architecture of the time’ and as ‘strictly functional’. Nevertheless, the setting of the fernery on the hillside, with its thick walls, towering south gable and curved glazed roof is extremely dramatic. The building takes the form of a stone casket embedded into the steep hillside with a glazed barrel roof.

  Wide-angle shot of the unrestored fernery and the rocky slope in which it is embedded
  Embedded in a steep hillside, the derelict fernery presented a challenging site for all concerned. (Photo: MAST Architects)

One can imagine Duncan’s visitors first marvelling at the stunning collection of paintings in his gallery and then being conveyed across his estate to his other secret treasure house, the fernery. Here they would have climbed the steps to a small doorway at the foot of the massive gable end and entered under a dark vaulted entrance porch. Stairs on either side led up to the broad middle level where the visitor finally emerged into a steamy, green paradise beside an ornamental grotto that arched over an oval pool. Here they would have been greeted by a profusion of ferns in every direction: beside the paths, rising up beside the steps, suspended from the walls and probably with the broad fronds of tree ferns silhouetted against the glazed roof. Steps and paths edged in white quartz formed a winding, figure-of-eight route for exploring the interior. To the left and right of the grotto two further sets of narrow stairs reached up to the highest level, under the short north gable and beside another fern bed constructed above the grotto. From every wall of the fernery cantilevered stones protruded, providing further platforms for plantings, while the damp exposed cliff face inside the fernery provided a further natural habitat.

With its south west aspect, the highest level in the fernery would have benefitted from sun for much of the day, while plants closer to the entrance, below the great south gable, would have been in deep shade. Hidden beside the paths were vents from the heating system, connected to an extensive network of underground pipes that conducted warm air from the boiler below. Upkeep of the fernery would have been a costly undertaking: glasshouses were expensive to maintain and the coal-fired boiler would have needed daily attention.

James Shirley Hibberd, a 19th-century horticulturist and editor of The Gardener’s Magazine, provided long lists of ferns recommended for cultivation under different conditions in his book The Fern Garden (1869). Hibberd advised on how to construct and lay out a fernery to achieve a natural effect, recommending building on a slope to gain from the range in temperature that could be realised in a heated fernery.

  The overgrown grotto with stairways to either side
  The grotto and stairways before conservation (Photo: MAST Architects)
  Overgrown gable wall with remains of the semi-circular iron roof trusses also visible
  The derelict fernery with its towering south gable (Photo: MAST Architects)

The location and construction of the Benmore fernery reflected these recommendations. It has a large rectangular footprint and was originally covered by a glazed arched roof. The three thick walls – the long west wall and the two rounded gables – are constructed of schist rubble and lime mortar, while the fourth wall is formed largely by the cliff itself. The fernery’s position at the side of a steep gully means that its floor is on three levels; the uppermost (north) gable is fairly low, equivalent to one storey, whereas the lower (south) gable towers up out of the hillside, reflecting the considerable change in height within the building. On the west side, at the lower end of the long wall is a small lean-to building where the coal-fired boiler was housed.

Remnants of the original roof of the fernery showed that it was carried on semicircular iron trusses, supported on buttresses capped with substantial padstones to spread the load. The glazing had been supported in wooden overlapping frames, presumably held in place with putty. However, the detailed structure of the frames had been lost, and there was no trace of the ‘lantern’ that ran along the ridge of the roof, other than the small gablets where it met the top of each rounded gable.


Following the introduction of a German sugar bounty, Duncan became bankrupt and had to sell the estate in 1889. It was purchased by Henry John Younger as a sporting estate and he introduced an impressive collection of rhododendrons. The fernery, being expensive to maintain, probably started to fall into decline following the change of ownership, but, while the picture gallery and sugar refinery were demolished, the fabric of the fernery remained, its isolated position perhaps helping to ensure its survival.

Through the generosity of Henry Younger’s son, Harry George Younger, the Benmore Estate was gifted to the RBGE in 1930. The fernery was already derelict by then and, although it was structurally maintained for as long as possible, some 15 years ago the building had to be closed to public access.

Unfortunately, no written or visual records of the fernery at Benmore in its heyday have been found, nor any reports of the species under cultivation, nor any photographic archive, and so we can only speculate on the diversity of species that were cultivated. Following exposure to the elements for probably a century it is not surprising that the original collection of ferns has long since disappeared. Prior to restoration, with the roof open to the sky, the derelict fernery remained a fernery of sorts nonetheless, having being invaded by a jumble of native species that luxuriated in the cool, moist and shady conditions. And in the year before restoration an exotic brittle bladder fern, Cystopteris diaphana, a species more commonly found in Madeira and the Azores, was discovered lurking in the grotto beside the pool; perhaps it was one of the original denizens.


In 1992 Historic Scotland designated the fernery a category B listed building, describing it as ‘a rare structure and important as an integral part of the gardens at Benmore’. Listing the building proved to be a great stimulus for generating interest in the surviving features, and its restoration was championed by the Friends of Benmore and, in particular, by the Younger (Benmore) Trust. Established by HG Younger in 1930, the trust covered the running costs of the garden and is now used to support projects within the garden. The trust was keen to see the fernery kept and accordingly commissioned a feasibility study by MAST Architects of Glasgow.

The detailed research required for the feasibility study revealed how the building had been constructed. The thick walls, tall gables, and lean-to boiler house appeared relatively unscathed. Much of the internal design was still evident even after 100 years of decay, although the vault over the entrance had been demolished and details of its construction were sparse. There were remnants of the staircases on either side of the porch, the grotto and pool had survived, and there was evidence of the upper staircases that led above the grotto. A few of the iron hoops that supported the original roof were also still in place.

  The fernery clad in scaffolding, boards and plastic sheeting Towering gable wall and new roof of the restored fernery
  Above left: work in progress (Photo: MAST Architects). Above right: the exterior of the finished fernery (Photo: Lynsey Wilson; RBGE)

A meeting on site between the architect, Michael Thornley, and Historic Scotland was critical to establishing whether any form of restoration was feasible. To reconstruct the glazed roof to the original design using the rather insubstantial iron hoops and conventional wooden supports would have created enormous problems for long term maintenance. However, as there was nothing left to indicate how the ridge-lantern had been constructed, nor how the structure was ventilated, its restoration would have been largely conjectural. It was therefore decided to put forward proposals for an entirely new glazed barrel vaulted roof constructed with modern materials. Historic Scotland concurred, opening the way forward for the conservation of the surviving features under new glazing; but there was still the matter of funding the project. This was achieved with the support of significant donations by the Heritage Lottery Fund, the Younger (Benmore) Trust, the RBGE Members’ Appeal and many private donations.

Restoration work started in May 2008. The site was secured and plant and facilities were brought in, including a crane to raise equipment from the work base at the bottom of the gully to the level of the fernery. The first task was to restore the walls. Scaffolding was constructed inside and out so that every area of wall could be cleared of vegetation and re-pointed. The upper walls and especially the upper gable ends needed particular attention. Significant elements had to be taken down and rebuilt. Regular meetings between the contractors, the architect and RBGE staff ensured that the challenges of reconstruction work were overcome. Despite heavy rain in October 2008, work progressed well during the autumn, and the final critical measurements could be made to allow accurate construction of the metal arches to support the new roof glazing. By early December the arches had arrived from Belgium and were being positioned so that by Christmas most of the glazing was in place.

  Sprouting tree ferns silhouetted against the new glazed roof and lantern
  Tree ferns flourishing in the renewed fernery (Photo: MAST Architects)

With the glazed roof and lantern in place, the internal scaffolding could be removed to allow work to start inside the fernery rebuilding the vault over the entrance, repairing the grotto, reinstating the paths and steps, and reconstructing the water supply. There is no electricity in the building; the ventilation in the lantern is operated manually, and the water supply relies on a gravity feed. The barrel vaulted glass roof has a curved ladder on each side to provide access for maintenance, and these ladders can be cranked manually to move them between the gables.

The completed structure, with the newly restored walls, wall heads protected by thick lead flashings and newly constructed glazed roof, is stronger today than when it was first erected in 1870, a fact that bodes well for its future.


The fernery was re-opened to the public in September 2009. In the absence of any historical records, RBGE horticulturist Andrew Ensoll has used his knowledge and long experience of fern cultivation to design the plantings, selecting ferns from many parts of the world for their diversity of form, as well as the diversity of their origins.

Most of the ferns have been grown from spores at RBGE, and over 75 per cent are of known wild origin. All are from temperate or warm temperate regions, with many from the southern hemisphere. They include species native to the Juan Fernandez Islands in the Pacific Ocean off the coast of Chile and others from the Azores, Hawaii, South Africa, New Zealand and Tasmania. Some are now rare in the wild and in need of conservation protection.

The Victorian fern craze is now largely forgotten, a curious fragment of Britain’s cultural and botanical history, but when visitors find themselves inside the restored fernery, a lush green world apart, they might feel a touch of pteridomania themselves. Furthermore, by preserving historic fabric and promoting biodiversity the project has successfully united two different but related forms of conservation. Both the restored building and the remarkable plants it shelters are the product of a belief that we have a duty to keep such unique treasures alive.


Historic Gardens, 2010


MARY GIBBY is the director of science at the Royal Botanic Garden Edinburgh ( and the president of the British Pteridological Society. Her research studies on ferns and their conservation have taken her from the Atlantic woodlands of Argyll to the Macaronesian Islands and Bhutan. She is the author of The Benmore Fernery: Celebrating the World of Ferns, RBGE, Edinburgh, 2009.

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