I think I'm going on my 3rd year with this Autumn Clematis, which is situated in part shade next to my garden shed. Every year it puts out lots of green growth and climbs all the way up to the roof on the strings hubby provided, but I only see flowers on the very top. I'm wondering if it's not getting enough sun? There is a successful Madame Julia Correvon about 3 feet away but it's more toward the sun than Autumn is. Should I move it, and if so, when is the best time?