What can I do to save/keep 2 Black and Blue Salvias I have right now? I do not have any seed. With already having some house plants and now bringing in some tender plants for the winter, space is getting somewhat limited in the house. Can the B&B Salvia tubers and stems be dug and stored similar to what is done with Dahlias?

I truly appreciate any expert advice/good suggestions to help me save these 2 plants. I live about 90 minutes east of the St. Louis Arch, on the edge of zones 5 & 6. One person I know had hers come back this spring, but I don't think B&B are usually hardy here. Thank you in advance for your kind assistance. Gina

ps: I had first posted this in a different Salvia post about seeds, but then thought that a new ? that wasn't about seeds might be the way to go. So please pardon any duplication.