I have a small garden at the back of our house and have quite a few of the elho planters that you hang over a fence. Some of them are the smaller ones with a hook at the back and a couple are the larger ones that sit on top. I usually plant them with annuals but this can be quite a lot of work. Would there be perennials I could plant instead? I was wondering about perhaps alpines? The spot is north facing but gets sun in the afternoon/evening. It is also quite exposed and has sub zero temperatures in winter. I don't want to plant ivy as I'm struggling to keep it under control in the front garden.