I have planted most of my selection in pots and have decided to put them on the roof. I plan to put a green net during the hot period.
I will have to bring down the best ones when in bloom, for display.
Sir i think the cemented roof top will get very hot in summers, besides Green Top, Few inches or soil/insulation of some sort can be used to keep the pots cool.
I have grown many plants on rooftop in small pots... none of them showed any damage from sun during summers... but there is a difference between Karachi and Lahore climate...