ETA 12/10/10: This was posted in response to a FaceBook post from someone in Florida that had two 250w heat lamps on their birds and it hadn't even dipped to freezing yet. I am not going to tell you NOT to add heat, but if you do, understand that you are restricting their normal acclimatization and will likely have to continue to pamper them through the winter. I personally cannot afford to heat all 4 chicken houses, and with careful observation have determined that they are perfectly fine down to 0F with so-so housing, and lower with properly set up/insulated housing. That said, continue reading! It dipped to 0F this morning. I knew it was coming, so I added fresh shavings to the pen, added a pile of hay in the corner, wished them well and said good night. Did I run around running extension cords from the house to plug in 500 watts of heat? No. Did I add any heat? No. I have ~ 20 12-16 week old juveniles in a hoop run - this is my "grow out" pen". The pen is about 10'x16', and is covered by your average tarp. Black plastic covers the areas that the tarp misses, but the end with the wooden door is open 1" chicken wire. It's not insulated, it's somewhat draft free, but with 20 mph winds, nothing is really draft free. And did I mention no heat lamps? All my babies were running around this morning like it was a summer day. 0F, no signs of frostbite, no signs of suffering... well, except for the fact that their water was frozen solid and they were thirsty... but they're happy now with fresh water. The adults were happy with fresh water, too. Did I mention it was 0F? And no heat? I'm just saying... SO many people ask when they should add heat. I understand... I'M cold! But I'm not wearing a down coat. I, for one, can do without a $600 electric bill for one month. Want happy, healthy, safe birds this winter? Hold off on the heat.