Q.Hydrangeas In A Pot Can They Stay Outside Over Winter
These are young newly potted plants

Yes, here in the Metroplex, it gets quite cold during January and February and a pot's material will not provide cold protection unless the pots are pots that are buried in the ground. Potted hydrangeas in pots should use rollers and then you can easily move them into the garage but, do not forget to water the pot now and then (when dormant, every two weeks maybe?). If temperatures are going to drop considerably like they did in February 2021, consider bringing the pots into the home until the temperatures warm up a tad (then move them back into the garage).