Now that fall has arrived, at what temperature should I start the heat lamp in the chicken coop? I know chickens are hardy and not to worry about them until the 30 degree temps set in. Also, should I use the standard red heat lamp that I used for the brooder or should I change to a white light bulb? My coop size is 4 feet x 6 feet that I purchased from Horizon. I have two set of chickens, one set is 28 weeks and the other set is 10 weeks. Total amount of chickens is 11. Current temp is 54 degrees.