I've never grown it in my own yard, but it's my understanding that it will come back in zone 5 if it's happy with its growing conditions. You might want to get a small one this year to try in the area where you want it and see how it does. If it doesn't make it, there are some lovely creeping veronica's that would accomplish the same thing. How about Turkish Veronica, V. liwanensis, or, my favorite, Veronica 'Waterperry', which is a very ruffly, lacy looking plant.

Skybird

I live in Michigan Zone 5. I lost half of the blue star creeper last year. I had it planted between stepping stones in very good draining planting mix, and full sun, part shade exposure. Quite expensive proposition at $60 a flat. I am understanding now, that it isn't that hardy below zone 6. I'm hoping someone can advise me also.