You could argue about whether the Victorians invented the greenhouse, but they certainly made the best greenhouses ever. Victorian greenhouses have a number of central design features that are still sought after by growers today: a steep roof of 45 degrees helps the light transmission and crucially, gives more height in the greenhouse. Specimen plants such as peach trees or banana plants love the extra height both for physical reasons and environmental; the extra height creates more air and a more stable atmosphere within the greenhouse.
Victorian models also tend to have period features. For example, both the Robinsons Victorian greenhouse and the Alton Victorian greenhouse have cast aluminium spandrels at both the eaves and the ridge. These add both strength and style to this kind of greenhouse.
Traditionally Victorian models may have had narrower glass panels than the now standard 2ft wide panels, however, the modern grower knows the value of high light transmission, so both the Robinsons aluminium Victorian and the Alton Cedar Victorian greenhouses have narrow glazing on the gable ends (for a victorian look) and wider 3ft wide panels along the length for better growing conditions.