In an earlier post, I traced the origins of the ivy that grew on the walls of the Van Vleck Observatory for much of its history. However, as you can see by comparing an early photograph of the observatory with the building today (below), the ivy has been removed. Why?
For decades, architects, scientists, and gardeners have been debating the desirability of allowing vines to grow on building walls. Some considerations were primarily aesthetic:
“A home should seem to be tied to the ground in such a way that it will appear to rise from it without a sudden and abrupt breaking of the surface.”
– N. H. Ellsworth, “Planting the Home Grounds: The Use of Vines,” House Beautiful, Volume 48, July 1920, 200.
“…nothing can be more unsightly than a good building metamorphosised with heavy growths of ivy or other plants.”
– Sir Thomas Jackson for Times, quoted in “Creepers on Buildings,” The American Architect Volume 120, December 1921, 14.
But others concerned the material impact the vines had on the buildings. According to a note in The American Architect and the Architectural Review of December 21, 1921 (below), even then, creeper plants were thought to be damaging to masonry. (Agreement on this point is far from universal. A 2010 study by Oxford University scientists concluded that ivy can act as a thermal shield and protect brickwork from intrusive moisture.)
From a closer look at the literature, it appears that the precise nature of the building material material determines whether a wall can sustain ivy without damage. Some ivy plants apparently secrete an enzyme that erodes mortar of the kind found on historic buildings like the Van Vleck Observatory. According to Dave Hall, who maintained the grounds at Wesleyan University for over 30 years, much of the campus’s ivy was removed precisely because it was damaging the mortar. It appears that the vines came down from the Van Vleck Observatory sometime in the late 1980s or early 1990s.