My baby chicks were hatched on Dec 14th. They spent the first 10 days inside under heat lamps and fed medicated food. I then switched them to the unheated but insulated and enclosed garage with a heat lamp which is where they have been for almost 3 weeks now. My next steps is to move them to a section of the coops which is blocked off from the rest of the flock, the plans are for this to happen the first week of Feb which should put them at about 6 weeks of age. They are getting kinda big for the homemade brooder and I think before too long they will be able to fly out of it. It stands about 3- 3 1/2 ft tall. I hope to get them out to the coop before that happens. When should I be able to let them out with the rest of the flock? I worry a little about them getting cold but also understand they are chickens. I do not have heat lamps in my coops. I see no real need for it. Chickens lived a long time as wild birds before people got involved. The coop is secure with a deep litter bed and it is insulated. So opinions are needed on when it would be safe to say " ok girls. Have at it and meet your new family"?