Has been grown for decades at the Seattle arboretum - and there are supposed to be/have been some old ones at an experiment station in BC.

Coldest winters singe part of the foliage of the arboretum planting(s). Named selections offered by local garden centers may or may not be as hardy as the form grown there - the hardiness of this species varies. You will have to try some and find out for yourself.

I have been growing both for about 8 years. I am at about 900' in north Clark County so we get quite cold, It has definitely been through 8 degree weather. Yes, they are evergreen. Yes, deer love to nibble the tiny new leaves!!!!!! The white flowered one appears to be the stronger of the 2 for me. It is sturdier.
Flowers often ruined by frost. Seem to be slow growing even when not pruned by deer. Can't discern any difference in tea produced. I know both One Green World and Nichols Garden Nursery carry them Both can be googled. Both sell mail order. jwww

Thank you both for the info. I'll find and get both. We don't have deer around here so they should be happy.

Raintree Nursery in Morton, WA. They are online and also will mail you a paper catalog.