For very low maintenance - varigated ivys are good for trailing and last all year round-in the winter mix with lots of winter pansys-really cram them in!
In the summer plant mixed coloured busy lizzies, again lots of them inbetween the ivys.
why dont you try tumbler tomatoes, they will need watering and a weekly liquid feed, and you will get the benefit of something to eat, from your efforts mullein