Having a flick through some old magazines I came across an article in Icon about this urban farm called PS1. It was an installation in New York by architects Work AC.
In cardboard tubes, 50 varieties of vegetables are grown, irrigated by collected rainwater and heated via solar panels. The spaces between some of the tubes allow for people to pop up and collect the vegetables!
I think it's a different way of approaching the subject of urban farms and at the same time producing something aesthetically pleasing.