Can a 5′ arborvitae survive the winter in a 3 gallon pot?
Certified GKH Gardening Expert
Arborvitae is a common and good choice for containers. Depending on your location and the severity of your winters, I would treat it as if it's in 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. Therefore, you may want to consider wrapping the container with burlap and place it near the home, if possible, to provide additional protection/shelter.
Depends on where you're located, how hard the winter is, and what kind of winter protection you use for the plant. This article has some suggestions: https://www.gardeningknowhow.com/special/containers/overwintering-container-plants.htm
If planting is at all an option for you, you might want to consider it. https://www.gardeningknowhow.com/ornamental/trees/arborvitae/growing-arborvitae-trees.htm