Every year! Ugh. Every year, I end up with some plants in containers I’ve neglected to plant, and it looks like this year will be no exception. Do you ever find yourself in this situation? Or maybe you just have some perennial plants you prefer to display in containers and want to overwinter them. I group mine in an open cardboard box in a pile of leaves out of the wind on the north side of a hedge to keep them out of the freeze-thaw action of the sun. Here are some tips for getting containerized perennials through winter. 
https://extension.psu.edu/overwintering-plants-in-containers