A brief Web search regarding P. mollissima's hardiness yielded results that were all over the place, from USDA zones 5 to 10. I don't know which ones are trustworthy. The "Plants for a Future" database showed extreme hardiness: zones 5 to 9, but this is a charity soliciting donations and may not care very much about the accuracy of its database.
thank you all. I will try to find some of those seeds and try growing them in my plastic greenhouse :)
