Trumpet Vines Not Flowering

I have had my trumpet vines for 2 years they are planted around a telephone pole in my yard the one facing the sun is growing nicely but has no blooms the one behind the pole doesn't get very big but it is still trying. At the end of season do I cut theese back before a frost or should I wait until the spring to cut it back. I would like it to eventually bloom and cover the pole I live in the PA area. Any suggestions would be helpful

Ellen, thanks so much for that information! I have always wanted a trumpet vine but I wasn't sure if I had a good spot to grow one. Now I see that I have the perfect place!