The hoop house and cold frame allow us to leave the seedlings out overnight during the early spring, even during short cold spells, mild snowstorms, and hailstorms in the early spring. The peppers seem to thrive just fine with some cover, as long as it doesn't get too cold for too long!
We also grow cool weather veggies like Spinach, Little Gem Lettuce, Beets and Green Onions in our cold frame and hoop house over the winter months. It's really nice having fresh greens in the heart of winter! The trick is to get them started early enough in August to get them growing strong before the cold weather comes to stay, as everything does grow quite slowly in November/December/January.
We were surprised that some of our pepper plant "test subjects" were happily growing even when nighttime temperatures dipped below freezing last spring. It depends on HOW cold it gets overnight, but apparently it didn't get cold enough to do any damage to the seedlings and they didn't seem stunted either with the extra protection.
Did you know that there are some peppers that don't mind a little cool weather?