In San Francisco there at least one building with trees and other greenery about 500 ft up at 1 Front Street. It has them on the 35th through 38th floor with a

In San Francisco there at least one building with trees and other greenery about 500 ft up at 1 Front Street. It has them on the 35th through 38th floor with a rather high glass wind shield that keeps parts from blowing off the roof. I know that's short compared to some of these massive skyscrapers they show, but as long as the building radiates heat back up at the trees, I don't really see why you couldn't go considerably higher.