I have several Calla lilies that I have grown in pots for a few years. Most are hybrids, but I believe that 2 pots are species due to the lack of capitalization in the name. The are referred to as 'giant white'. They only bloomed for the first summer. I bring them in after frost. I recently discovered that they aren't dormant but are currently growing in my basement. It is dark and fairly cold, slightly above freezing. I suspect that is why they don't bloom. How do I get them dormant or, more importantly, what does it take to get them to bloom again? The hybrids are easy and reliable and they are all grown together.