sally:

Too many chill hours isn't an issue, but extreme cold would be. I'm not sure how cold is too cold. On the border of z6/7 you are probably OK, at least most years. But there is another issue that could be critical, bloom date. This cultivar is going to bloom very early. Around here it would get frozen out every spring. My solution is a pot and a greenhouse. But a pot and another form of shelter is certainly workable.