Answer: I hope it is not already too late to move it inside. This is a tropical plant and the tuber is damaged by temperatures below about 45 degrees. If the tuber rots, the plant will die. Ideally you would bring it inside before the ambient temperatures drop below 50 degrees.
In order to grow well indoors these sunlovers need the maximum possible amount of sunlight -- these are tropical plants after all. In lesser amounts of light they will languish but survive; in lower light they will do better with lower temperatures (say in the 50's or low 60's) which help them to slow down naturally rather than keep on trying to grow full tilt and becoming leggy as a result.
Check it carefully for pests when you bring it inside, rinse it thoroughly with plain tap water and/or use commercially formulated insecticidal soap per the label instructions to remove any pests. Once indoors, as growth slows down with the shorter days, reduce water and fertilizer proportionately. You may find that it loses its foliage after you bring it inside, this is somewhat normal -- especially when it has been stressed. If it does become leggy or lose some foliage, simply trim it back a bit next spring just as it begins to grow again. Since it has already been exposed to so much cold, it probably will not bloom for you indoors this winter even under terrific conditions.
Next spring, when the weather moderates, gradually acclimate your plant to the full sun to avoid "sunburning" the foliage and adjust your watering and fertilizing as it begins to grow vigorously again. Good luck!
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