All 3 on your list are perennials. The calibrachoa and petunias would appreciate a cold location with some light while the impatiens will want warmth and good light all winter. I have calibrachoa that are going on 4 years old.

Al

This is promising! Since the calibrachoa and petunias are already very leggy, should I cut them back sharply?

Now I only hope I can remember to go down in the basement occasionally and water the!

The petunias can be cut back hard with no problem, but the calibrachoa is more fussy. They tolerate a hard pruning when they're growing well, but when indoors, it's best to do it incrementally. I always try to prune any plant I might winter over for bonsai training two weeks before I bring them indoors so dormant axillary buds get a chance to start growing. They always rebel at the change in humidity & that change, along with a hard prune can be more than they'll tolerate.

Al