Well, we had snow today, last night and hail yesterday afternoon, preceded by several nights of frost and low temps, about 32 F or a bit below that. I didn't get the tomatoes in until late last night. They were covered with plastic, but that's all. They are just fine, and taste very nice. The name of this sturdy breed? Sweet Million, a cherry tomato. It's very prolific. I'm definitely going to grow it again. Lucinda, USDA zone 5, Great Lakes region, Canada