As if growing in standard horizontal greenhouses isn't difficult enough!
The idea of a vertical greenhouse for cities intrigues me, though, as do other greenhouse projects that seem out of this world (i.e. building a greenhouse on the moon). According to the story I found, an inventor came up with the vertical greenhouse idea 20 years ago, but he was essentially laughed at and turned away everywhere he pitched it. Ten years ago, the inventor pitched it to Plantagon vice president Hans Hassle, who made a commitment to build vertically.
Now, Plantagon is peddling the vertical greenhouse as the urban marketplace where urban dwellers (i.e. consumers) can buy their fruits and vegetables.
I'm not as familiar with the European landscape, for which vertical greenhouses are probably better suited, but I can't imagine any U.S. cities seriously considering construction of an vertical greenhouse -- particularly for the $30 million price tag each installation would cost.
A first impression of the major U.S. cities nearest me (Cleveland, Detroit, Columbus, Cincinnati) is they're not as suitable for comfortable living as the suburbs or rural areas. Cleveland's population has declined dramatically in recent years. People are moving to the suburbs and are subsequently getting their fruits and vegetables from grocery stores or local markets. One massive grower-retailer here doesn't make sense. I'd be curious to see how fruits and veggies from one massive grower-retailer in cities were priced.