Jim, I have the plant growing here in Venice Beach so I can't really help with hardiness questions. It grows really well in moderately moist soils in full coastal sun. I have one in an area that gets less sun and it didn't do as well. I've often wondered about the hardiness of this plant as Tsuh Yang has asked me about it but I couldn't find out anything. Now maybe someone will step forward and find out. Maybe we could get Panayoti K.to join our online list?? He could answer quite a few questions that many of us have. I have several species of Sisyrinchium and all of them are very rewarding plants. I would love to get more. But, I have killed quite a few of them as well. Many of them do not like to be grown in pots and they dry out too quickly this way. John Ingram in L.A., CA. http://www.floralarchitecture.com/ "Your Clivia Connection" john@floralarchitecture.com 310.709.1613 (cell, west coast time, please call accordingly. Thank you)