I want to plant an area of my garden that has reasonable sun in summer, but
is completely in shade all winter.

I have some extra perennials from dividing and cuttings, but they're
generally considered sun-loving (achillea, campanula, phlox, aster).

The perennials are dormant in winter when they'll be completely in shade,
but they'll get sun in summer when they're growing. So, will they get the
sun that they need to grow well or do they have to be in sun the whole year?

Thanks,