Zone 5 Amorphophallus Konjac - first winter.

I read that they may not survive the winter so I put them (two bulbs) in pots instead of the ground. Both plants sprouted a fleshy stalk which opened up at the top and grew some branches (about 1' tall x 2' wide). I brought them indoors before the first frost and have continued watering them. One is healthy looking as ever but the one closest to the heater is drying up. Probably just needs more water but my questions....
Should I keep watering them or do they need to hibernate to eventually blossom? Will the stalk naturally die even if I keep watering it? If I dig them up to store in a dry place, how much of the stalk should I leave? Does it matter?
Thanks! -Ian-

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