Astilbe is a perennial that is hardy to zone 4. It can tolerate full sun, but it's best to give it a little shade, otherwise you risk scorching the leaves. This plant bloomed for me in June. I bring it to your attention now because soon, the garden centers and big box stores put their perennials on sale. That's a good time to buy some new plants. Don't be afraid of the ones that look a little unloved. They often bounce back in time.
You can go ahead and plant perennials in your containers and they should survive the winter if they are suitable for your hardiness zone. But remember, my rule of thumb is that for containers, subtract 2 from your region's planting zone. This is because when a plant is in a container, it is more exposed to the elements than when it is in the ground. Where I am in Northern Virginia, my hardiness zone is 7. So I look for perennials with a hardiness zone of 5 (or lower). Also, make sure you don't plant in too small a container. The more insulated a plant is by soil, the better chance it will have of surviving.
Bookshelf: Container Gardening Books