I live in Gunnison CO and it gets really cold here at winter. We have at least 2-3 weeks of Subzero weather (-20 to -30F) at least for the nighttime lows. I have 18 Rhode Islands right now- however 8 are roos and will not make it over the winter (they will be sold or eaten) So assuming I have 10 hens in a 4x5x5 non insulated coop and I have a heated waterer...do I need a heat lamp? My other variable is they are only 3 weeks now...that puts them 3 months old by Christmas. We will also probably have 18 chicks when then are still 3 months old. We have a theramacube that can turn on a heat lamp on at 20F and off at 30F. Is this necessary? What are thoughts and opinions on super cold temps. I picked RIR because they are hearty in cold weather. Any advice is wonderful as this is my first time with Chickens.