I don't think you can grow bougainvillea outside where the temps go below freezing. It's pretty tropical. Lack of water is good, they don't like wet feet and they bloom when they have been almost water starved for bit. Lots and lots of full, hot sun. Actually the location sounds great except that in that zone I think it freezes. Bougainvillea does not cling or attach to anything, it has to be supported to climb walls. It also has very wicked thorns, something to think about near a front door. It grows well in containers as it likes to be root bound, so perhaps it could be moved in the winter? It also does well if pruned rather severely every year, it keeps it from taking over and it is very painful to prune when it is really large - did I mention the thorns?
