For many gardeners today a greenhouse may be made of plastic, perhaps with aluminum framing.
However, in the 1830s, one builder of greenhouses was Joe Paxton, the relatively young head gardener for the Chatsworth Estate, owned by the Duke of Devonshire. By 1840 Paxton had already designed and been responsible for building a huge greenhouse there, a structure not much smaller in ground area than the area of a football field [ref.3]. Despite the known existence of alum for thousands of years, aluminum did not become a usable cheap metal until the 1880s, and Paxton’s greenhouse used cast iron for framework. Nor was it possible in the 1840s to make big sheets of glass, the maximum size of a glass pane then being only about 4 ft. by 1 ft. So his football-field-sized greenhouse utilized many thousands of these small panes.