Amazingly, I just discovered my Colocasia 'Thailand Giant' actually overwintered. It bloomed and died to the ground last late summer and I dug it up, potted it, and put it in a heated closet in my basement (and lit with grow lights for my other plants). It never showed any life, but I splashed a little water on it on occasion anyway. When I moved everything out to my unheated greenhouse this spring, it went along for the ride. I uncovered my greenhouse and let the rain water everything. I was SHOCKED to find three pups poking up out of the pot today. So, I guess not impossible to overwinter indoors. Two little green pups that I tried to overwinter the same way died quickly and I haven't seen any life since.
