Well I do not know if this helps, but I have germinated Dierama, which srats to grow here (Z5a, Hungary) in September, when temperatures start to drop, and want to grow in winter. So I have after 3 years only one corm left around the size of a half pea. And it turns yellow in march or april. Unfortunately I do not have a greenhouse so I keep it as I'd feel enthusiast... Bye, Jani