bout some rex begonias this year, planned to treat them as annuals. they are doing great in pots on my north facing full shade front porch and I can't bear to let them die this fall when Jack Frost comes to NY

i have no idea how to care for these inside. these are tuberous begonias right?
do they need the same care as reiger begonias? (that would be a shame, because I stink at these indoors in winter.. i can never get the humidity right.. )
is arranged/planned dormancy an option? can i let them get cool and dry then store them dark cool dry?

what is their low temp tolerance? in other words at what night time lows do they have to come inside?

do they mind being rootbound? they've gotten pretty big over the summer and I always feel better with tightly rootbound plants because the uptake of water tends to be more consistent throughout the pot and less likely to root rot over winter indoors.

Those are beautiful! I don't do anything in particular or different to save Begonias like that over winter, from any of the other plants that come inside. I bring in way too many plants to offer specialized care. Just carry it in and try to put it near a sunny window, water before the soil gets all the way dry.

They look like rhizomatous Begonias to me, not tuberous.

agreed, they look like ones commonly grown inside, and they are gorgeous!
also agree I would avoid any upotting now.