Well I know that if you want
spring and fall with a pink color you can do snapdragons,
Hollyhocks also come in a variety of pinks and bloom during the summer. But they are biennial so they only do foliage the first year and then
flower the second year and then die. So you need to
plant two years in succession. After that they will reseed by them selves to keep their beds full of
flowers.
And of course there are subzero
roses that come in pink which will definitely give you color all through the late
spring to early fall.
Good luck with your garden.