Q.Trees Grown in Containers
I live in Zone 5 and would like to know what trees planted in containers can survive the winter outdoors?

Certified GKH Gardening Expert
Arborvitae is a common and good choice for containers. I would make sure that you choose a tree that can survive one growing zone lower than yours. Plants in containers experience weather more like zones one lower because they do not have as much protection from the cold for the roots as plants in the ground.
These articles should help: https://www.gardeningknowhow.com/special/containers/how-to-grow-container-trees.htm
https://www.gardeningknowhow.com/ornamental/trees/tgen/growing-trees-in-containers.htm