I am finding this forum very interesting. We are currently in a 5b zone (SW Ontario) and previously lived in a 5a zone. We haven't been 5b for long - this is our third and by far harshest winter, so I'll see what happened in a couple of months. However, we did experience winter loss of a few cultivars at our old house, and what is interesting is that they appear to be relatively mixed. We have about 250 cultivars, and have lost 6. Three are Evergreen, and three are semi-evergreen. Four were actually picked up in the Carolina/Florida areas, and two were local big box store tissue culture. At the time I bot the big box ones, I was ignorant about tissue culture, and have since stopped buying them. Not necessarily because of survival issues, but also because of stability issues. I have bot a total of six tissue culture plants - two have died, two have "morphed" over time into a plant that does not at all look like what was originally there, one appears to be doing just fine, and the last I've had for years, but it is extremely slow to multiply.
So I guess what I am saying is that I'm finding the habit issue a confusing one when considering winter survival, and I'm also saying that the tissue culture process might have an impact on winter hardiness.
Can anyone else comment?
