I've found it easy to handle on a cool (above freezing porch). The cuttings also root like crazy. Outdoors in my warmer zone 6b climate it will normally make it through the winter in the ground, but I take a few cuttings just in case. By late winter they are usually flowering indoors.

How big does it grow in a pot? Here it has no trouble reaching 7 feet when planted in the ground. That is if it is staked. Otherwise it falls all over everything. It's great for hummingbirds and butterflies.

My Salvia uliginosa plants in the ground do not necessarily come back for me but they reseed every year in my zone 6 garden. I don't know if this would occur in zone 5 though, but you could always save some seeds if the plant is still in bloom and sprinkle them on the ground in the spring.