I don't think you have to heat your coop at all, but yes the plate warmers work when it's below 50 degrees. Mine was working last week when it was down to mid twenties at night. If you have plenty of ventilation, that doesn't blow directly on the birds, and you keep a dry coop, you can forgo heat altogether. Many people on BYC insist that is the best way to go. Wish I had started out that way, but afraid to take my heat plate away at this point. Until this year I used the red bulbs, but I had one break last year. That scared me and that was the end of that. Glass was everywhere, but it could have been worse. it could have started a fire.first off thanks for the warm welcome everyone. ValerieJ yes I have the coop and run built. The coop is 16ft x 8ft and the run is 14ft x 7ft with a metal roof. In side the coop there are 2 sections.The hens and rooster will be in a 8ft x 8ft area and the meat birds will be in a 8ft x 6ft.Then they will both have a 14ft x 7ft run each. Now the question I have is if I don't want to go with a heat lamp what are my options for outside use.Early April here in Iowa can be warm or cold. The plate warmers won't work if it's below 50 degrees.I'm looking for some ideas.