Ideas for plants in hanging pots

Hi All. Had an idea of hiding part of fence with square wood trellis and to have hanging pots on it like below,Elho Corsica Easy hanger.
They are 2.4 litre capacity but I did not think it through as to what to plant in them. I do have Erodium Bishops form to go into one put but after that I am stuck We have a total of 6 pots and ideally would like to plant something permanent like perennials/rockery alpines.

Again it would be ideal if plants were summer flowering but not sure if any rockery/alpines flower summer long and again if a perennial would grow in what is a basically a small pot. Any ideas would be grateful.
Thank you