I am in zone 5 and have very good luck with several perennials in out door containers.
In shade I like a hosta ,coralbell combo with a few annual inpatients or coleus added for color.
In sun I would do herbs, chives , oregano , thyme,all will come back and a staple to any kitchen then add basil (annual).
Herbs take less water than most plants and will still do well.
