I didn't know Salvias were so tough or long flowering

Despite temperatures dipping below the freezing mark this Salvia keeps flowering - at least those in slightly protected areas. I bought a packet of seeds two years ago and broadcast it in the open space between shrubs. It dies back in winter but self seeds and we've had as many plants this year as last. I'm guessing but it's probably a variety of S. officinalis or pratensis. It grows quite tall and will fall over in a wind but a stand of it holds up quite well. We love the look of it so put up with the few that fall.