In my experience these are very cold hardy, and mine survived being covered in snow for about 3 days ... they need some cold to generate flowers also. Some varieties of this plant and survive up to -25 celsius. But i wouldnt let mine go under -10 celsius just to be safe.

Mine are out doors in a 3 " pot in zone 8

sweet....thank you

Mine are planted outside. I cover them with a pot during winter rain events.