When it comes to elevating vegetation atop a man-made structure, consider these two extremes: a highway billboard overtaken by kudzu and the Hanging Gardens of Babylon. While the former simply happens on its own, the latter -- one of the Seven Wonders of the World -- required quite a bit of effort and ingenuity, much like today's living billboards.
Installing a living garden atop a sign requires more work than what usually goes into typical billboard. For instance, the team at Leo Burnett didn't just glue a bunch of potted plants to its Chicago billboard. Team members hired a horticulture expert from the University of Illinois to implement a patented Canadian vertical growing method. The complex structure underlying the sign involved the use of soilless soils and an irrigation system. Plus, the firm had to alter its original time frame for the campaign to meet the needs of the plants, as the lettuce wouldn't have coped well with the summer heat [source: Larson].
A winning entry from the 2008 International Design Awards (IDA) Land & Sea Competition took a promising approach to the notion of a living billboard. TODO Design and Das Studio presented plans for a billboard structure that greens up the area surrounding the sign, while not actually playing a role in the advertisement. The design calls for water to be raised to the billboard's potted plants via a pumping system that, in turn, is powered by solar panels on top of the structure [source: IDA].
Environmentally friendly technology often plays a role in green billboard designs. In fact, Japan's Ricoh Company Ltd. launched a billboard in New York City's advertising-heavy Times Square in January 2009. The buildings in the area are crawling with brightly lit advertisements, like a kind of urban kudzu, but the $1 million Ricoh sign gets all of its electricity from solar panels and specially designed wind turbines [source: Gruber].
Of course, as any fan of the television show "Mad Men" can tell you, advertising executives and hippies don't exactly see eye to eye on everything. Are living billboards truly green, or are they greenwashing?