Q.My Japanese Aralia Plants Were Bady Damaged During A Hard Freeze. How Should I Trim Them Back?
The aralia plants were planted this past spring.

Certified GKH Gardening Expert
Typically, these are pruned completely for restorative purposes. It would benefit them to have this done right before they start actively growing for the year. It is getting close to that time, so doing so now would benefit your plants.
Here is an article that will help you with the, general, care of your plants:
https://www.gardeningknowhow.com/houseplants/aralia-plants/japanese-aralia-care.htm