i had read they could be hardy to 8
but, i also had read several accounts of people not being able to get them, to fruit.
i thought maybe they had "chill hours" like a blueberry ?
i do have a spot in the yard taht can give them afternoon shade and morning sun
its also fairly moist
One spot may be too moist, as it can rain for 3 days straight here sometimes
and saturate the ground (as well as humidity being very high)
at times we can go a month +, without rain too.