Wow you really is serius! iÂ´m impressed! Very nice data to have. A small note from me and my maples. The big thing to get them to survive here is to have as long period between the frosts as possible. The last spring frost is said to be jun 4 and the first frost in autum in mid september. If you shelter them from the first frosty nights you can have another month without frost. And another thing is that our(mine) summers is not as warm as they are in winnipeg. About the winter cold , i had over 2 weeks over -25 C. But i dont think the winter temperatures matters so much -10 or - 30 doesnÂ´t make a big differens on survival ,but longer growt period does. The thing about sweden and norway climate is that the gulf stream keep us warmer than average citys in 63 degree N. Hope this info helps.