Yes, I think many plants, which are classed as not hardy for our zones, have not been tried here.
By trying them as annuals first, they may came back some years.

Anderwood said:I don't mind buying a butterfly bush (budleija) each year. Maybe with any luck, mine will come back this year. It is up against the house, and piled with snow. It is blocked from north west winds. Fingers crossed!

I had a Buddleia that came back several years and then one year it just didn't. I felt very lucky each year I saw it's little green sprouts reappearing:)

I have been wondering what it meant when a particlar seed was noted as "FasTrax".
I thought that maybe they had treated the seeds so they would germinate quicker?---
Wrong! It means that the seed will result in first year blooming plants.
The Benary people of Germany are using this as a way of promoting perennials which will bloom without any vernalization. i.e. bloom the first year.