I live in zone 5, we get many winter nights below 0 here, and I never use heat lamps. I have the heavy breeds. I don't force laying with lights either. I used to do that, but the hens would burn out in a couple of years. By letting them rest in the winter, they live often up to 9 years for me, and lay nice big eggs. (I can't seem to get one to live more then 9 years) There are some that will lay eggs all winter long even in the cold, but of course I have to collect them often so they don't freeze. If egg production for sale is your goal, then you would want to use lights, and replace the hens every year or two. I ususally let one hen raise some chicks each year for replacement hens, and a few roosters for soup in the winter. I didn't this year, as I am at full capacity now. They are fun to have around, they pick up lots of the feed that the horses would waste.
