I usually have my Dad bring in his Mandevilla inside and let it go dormant in his basement for the winter. It had done well for him for the last few years. Only issue seems to be that it takes forever for it to start blooming again. Usually doesn't bloom until August. I have heard others say the same time about how long it seems for their Mandevilla's to start blooming after being in dormant winter storage.
Gordon your roof top gardens are just beautiful.
