Wow, that looks like a great space for gardening. I love the view and it looks like you've got some nice plants there already; a couple of Crepe Myrtle trees blooming all summer will really brighten it up!
Rooftop gardens are such a great concept! I've never been to N.Y. city but always thought of it as a cold place with nothing but cement and skyscrapers ... until I saw Gordon's photo's!! It's wonderful to be able to bring greenery and a garden to the roof.