Hi balconywoman. I'm a newbie at balcony gardening... so this message is more to support you in your efforts, and let you know I'll also be looking forward to your responses here. I recently moved to a home which has an east facing balcony, and I'll be interested in learning the same thing as you... how to overwinter perennials that can provide greenery and colour year-to-year. I'm in Peterborough, Ontario/Canada. I believe it's Zone 5.

Let's see, somebody else just wrote in asking about overwintering their clematis, that's a really beautiful vine that would do for both of you (most varieties are hardy to zone 4 or even 3 in the ground), if you grow it on the Eastern side it should be really nice. Apparently jasminum polyanthum is hardy to 10 degrees as well and then you'd have some fragrance too. Cestrum nocturnum (night-blooming jasmine), hardy to 20 degrees.

In general, as winter approaches I'd cut the vine back almost to the ground (leave a few buds), mulch the pot heavily and bubble wrap it. Remember, in the ground the earth keeps the roots warm, but in a container the roots will freeze much faster if you don't protect them.

Keep watering to a minimum, because if it freezes in the pot the plant's doomed, and don't fertilize. Balconywoman should probably be able to leave everything on the balcony all winter (zone 7 means what, winter lows generally not lower than the 20s?), but faysie may want to move the pot inside if a really nasty cold front threatens.

Congratulations. For color you can add hakone and other heuchera. There are small azalea that will grow in a container, provide green background and color in the Spring.
Enjoy.