Nature Hills Gardening Neighborhood

I live in a cold climate and I have never seen a roof top garden except for on tv and on the internet.  I wonder how far north you can grow these.  I think it's a great way for creating more green spaces in cities.   

I would say that these are even more suited to cold climes than warm ones. You see the garden would benefit from the heat rising from the house and so be protected some from the colder weather. Additionally your house will be protected from the sun in the summer and will be extra insulated in the winter. 

This is VERY popular in the city- I grew up in North Jersey with my mother and spent my summers in NYC with my aunt.  She had the most beautiful garden getaway on top of her building- you wouldn't even think you were in the city when you went up there it was sooo serene- and since she lived on the east side- she has a birds eye view of the empire state building from her bedroom window as well as the rooftop :)

 This is popular and very beautiful from the sky view.  I have flown over some parts of town and patches of fresh green grass were everywhere on the tops of apartments and office buildings.  Some comapnies are actually growing their own fruits and veggies on the roof to serve to their employees in the cafe.  I think I saw something like this on the Travel Channel.  They were talking about extreme work places.