Not sure why no one has answered this. I am far from an expert so all I can tell you is what I do. Konjac is usually pretty well behaved and goes dormant with the onset of cool weather, mine is potted so I dig it out rinse it off and on the shelf in the basement it goes w/ dreams of a stinky March awakening. Some people leave them in the ground year 'round because they are pretty COLD hardy. What they are not is COLD and WET hardy, so keep 'em dry..

Some of my others (asterostigmatus, bulbifer etc.) got an early start and have gone or are going dormant now. Dunno what triggers dormancy but my guess is photoperiod. Some I will leave in the very dry soil in the pot, others I will lift. Dunni, Variabilis and some others were very late coming up and I will probably have to grow them on inside if I want to maximize tuber growth for next year. Some others (I hear titanum) just go dormant when they feel like it or if some physiological temperamental peculiarity or slight change in conditions triggers dormancy.

I guess the short answer is... depends on species and conditions. Hope this helps?

Maybe someone has some more/better info on this?