What to put in planters for north facing garden that gets lots of sun in spring/summer but all shade autumn/winter

I have quite an open square garden that despite being north facing has full sun pretty much from April to September and then full shade from October to March.

I’m building 2 long planters and would like some all-year round foliage that’s easy to maintain and can cope with all seasons.

Would really love to get some colour/flowers in there too but having tested marigolds, herbs and lavender this summer, they struggled a lot with the heat/light (thyme and rosemary lasted a couple of weeks max.)

Any recommendations for this sort of space? 🙏