My first set of chickens are now about 5 weeks old, I think - they have most of their feathers. Still some fuzz on the head and neck (not much!). Under wings is not full feathered, and their butts are still fluffy. Last night here in S. Florida it got down to 48*. I've been putting them in the coop in the mornings, bringing them in at night. At what age should they be able to stay out all night, even if it gets in the 40's? The coop is designed for S. Florida, not to hold heat. So they're in a cage in my extra kitchen. I love my chickens, they're so sweet, but they don't need to live in my house! I still have infants in the brooder, it will be a while before they even go outside at all. The last chicken I had was a pet - she died before Christmas at 9 yrs old from moulting. So sad - I miss her! She laid eggs almost the whole time - Arucauna. Years ago She began to steal sips of coffee, which stimulated the egg production, I believe. So I continued to give her coffee once or twice a week. She was a spring chick, so I didn't have to worry about the weather for her. Oh - she also ate dog food - Purina, green bag - she would only eat the orange triangles. I think they might be cheese flavored!