Well I know they are deciduous that's why they lost their leaves. And taking the fact that they are bulbs I would say keep them slightly dry during the winter to avoid rotting. I only had them for one season before I sold them (not because they were difficult but because I just needed the money for something else). They are great little plants. Here is a link that may help you identify the varieties you have and also give you a little more culture info: http://www.miniplantkingdom.com/search.cgi
They are not very hardy, native to South Africa. Should be fine in the winter if your zone 7+. Keep them quite dry during the winter, they should be treated like cactus, dry and cool during the winter.