Should I cut them back in the winter? I live in the north east.
Certified GKH Gardening Expert
It isn't completely necessary, however they flower on new growth, so it will not hurt them to do so either. You can prune back in fall, or winter when they go dormant.
Here is an article for more information on these plants: https://www.gardeningknowhow.com/ornamental/flowers/gaura/growing-guara-plants.htm