Last edited 11 Feb 2024

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Institute of Historic Building Conservation Institute / association Website

The wrought-iron greenhouse at Felton Park

The design of the rare, curvilinear wrought-iron greenhouse at Felton Park, Northumberland, reflected theories on the optimum design of horticultural structures.

Greenhouse at Felton Park.jpg
The wrought-iron greenhouse at Felton Park. The greenhouse was erected in two phases, probably in the 1830s. Photo by Edward Diestelkamp.

The Grade II* listed greenhouse at Felton Park in Northumberland is a rare example of a curvilinear wrought-iron greenhouse. Only some 20 examples are known to survive. Documentary evidence for its erection is not known to exist. Although it is not considered to be one of the earliest examples dating from the 1820s, the greenhouse at Felton Park was erected in two phases, probably in the 1830s, before the glass tax was abolished in the 1840s and developments occurred in the making of glass.

During the early 19th century, the writer and horticulturalist John Claudius Loudon promoted the concept of curvilinear wrought-iron glasshouses, and encouraged improvements in the creation of artificial climates and in the design and construction of hothouses, greenhouses and conservatories for producing domestic and exotic fruits and housing botanical specimens.[1] Loudon’s horticultural publications were widely read by gardeners and owners of gardens who wished to enjoy such delights. His extensive knowledge, combined with a fertile imagination, conceived novel forms, constructional methods and details for hothouses. Loudon was a prolific author, producing illustrated books, pamphlets, encyclopaedia entries and magazine articles which considered scientific and technological aspects of designing glasshouses.

In the early decades of the 19th century, horticultural and botanical societies such as the Horticultural Society of London enabled the exchange and dissemination of ideas and theories on the optimum design of horticultural structures through lectures, discussions and the publication of illustrated papers by horticulturalists and gardeners. The owner of Felton Park, Ralph Riddell, was a fellow of the Horticultural Society of London, and Mark Robson, the gardener at Felton, was awarded in 1823 the society’s Banksian Medal for grapes that he exhibited. It is likely that Riddell and Robson would have been familiar with the lectures and the society’s publications on the improvement of the design of glasshouses, and with Loudon’s writings on the subject.

Two related design aspects of the curvilinear glasshouse with which Loudon was closely associated were, first, the use of wrought-iron for the glazing bars in the construction of hothouses and, second, the optimum form that a glass roof should adopt to gain the optimum benefit from the rays of the sun in horticultural production. The use of iron in the construction of glass frames had been advocated earlier by the French botanist Michel Adanson in his Familles des Plantes (1763), for the slenderness of structural iron members in relation to their relative strength when compared, for example, with timber. Rather than wrought by hand on a forge, Loudon conceived of a glazing bar manufactured in a single piece by means of passing hot malleable wrought-iron through rollers. The first examples were produced with the expertise and skill of a foundry in London, W and D Bailey of 272 Holborn. Loudon soon afterwards passed the rights of the invention to William Bailey, who entered a patent in 1818 entitled ‘Windows & C’, No 4277, for the wrought-iron glazing bar.

In a letter read to a meeting of the Horticultural Society of London in 1815 ‘On the Form which the Glass of a Forcing-house ought to have’, Sir George Mackenzie proposed the adoption of a quarter sphere as the optimum form for the glass roof of a hothouse, a portion of which sometime throughout the day would be perpendicular to the rays of the sun. Loudon and others, recognised that the strength of the sun’s rays was limited during the early and late hours of the day and throughout much of the day during winter months, They therefore suggested that principles published by the Dutch botanist Herman Boerhaave in 1732 in Elementa chemiae should be adjusted to account for the strength and heat of the sun’s rays at different times of the day and in different seasons of the year, and that consideration should be given to the proximity of plants being cultivated to the surface of the glass itself. Loudon preferred an elliptical or the segment of an elliptical form, where the sun’s rays would be perpendicular to the glass surface during the middle hours of the day in the spring and summer months when the sun was strongest.

Following the production of the wrought-iron glazing bar, several early examples were erected by the Baileys of Holborn and others. At the same time patents for ‘metallic’ hothouses with glazing bars made of copper were developed by specialist manufacturers in Birmingham, an important centre for metal trades.

Urgent repairs to the greenhouse at Felton Park were undertaken by previous owners of Felton Park in the 1990s, with the support of the north-east region of English Heritage. In 2008 the greenhouse at Felton Park was included in the region’s buildings at risk register, and in 2013 the archaeologist Harry Beamish was commissioned by English Heritage to write a report identifying the significance of the greenhouse that established its rarity and importance.[2] At the same time English Heritage published a technical report by Vanessa Castagnino on the chemical analysis of the greenhouse glass.[3] In 2014 trial repairs to the greenhouse were undertaken to learn more about the condition of the structure, determining the best methods to adopt for its full repair. The following year an extensive repair programme of the greenhouse, and of the bothy standing behind it, was undertaken by the owner Tim Maxwell and led by Robin Dower of Spence Dower Architects, with the aid and support of English Heritage, the Heritage Lottery Fund, the Country Houses Foundation and Northumberland County Council.

Tim Maxwell commissioned Alan Fentiman to make a film about the restoration of the greenhouse and has created a website explaining the project. [4] The conservation repair is the subject of a detailed illustrated report by Robin Dower.[5] Calibre Metalwork was the main contractor and metalwork specialist, and Cheshire Stained Glass was the glazier.


This article originally appeared in the Institute of Historic Building Conservation’s (IHBC’s) Context 177, published in September 2023. It was written by Edward Diestelkamp, who teaches for NYU London in the MA programme historical and sustainable architecture.

--Institute of Historic Building Conservation

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