Hey folks! I'm working on a greening project in Montreal, Quebec; and I was wondering if it's possible to grow vines (virginia creepers & boston ivy), from the ROOF, DOWNWARDS. That is, they would be planted in a very large container on a rooftop and expected to grow down the wall, instead of planted at the base of a building and grow upwards. I need to know if they can be trained to grow downwards, attaching to the stone in the same way as when they work up a wall. The reason I need to know is because we're interested in greening the walls of some buildings but can't get excavation permits for the base of the edifices due to wires, gas lines, etc etc... Anyone have any experience with this? Any information you can offer will help a lot. There is nothing about this kind of thing being done that I can find on the web. Thanks!