Three clematises (Ascotiensis, Margaret Hunt, and Avant Garde) are spending the summer in large pots on my deck in anticipation of being planting this fall.

One of my target spots gets sun all morning but none in the afternoon. Currently, Margot Koster, Alba Luxurians, and Sizaia Ptitsa bloom there very happily. But there are lots of shrubs (mine) and trees (my neighbor's) around. I'd like to put Ascotiensis there, but it seems to me I've heard it has a propensity for mildew. Might it be happier in a sunnier spot? Any speculation as to which of my three candidates might do best in this situation?

Pat