It can be hard to completely prevent frostbite in wattles and combs in freezing weather. Raising waterers or using nipple waterers may help, but keeping water thawed can be challenging. I use electric dog bowl waterers set up at shoulder height. Preventing moisture and high humidity, keeping them from getting combs or wattles wet, making sure bedding is dry, and having good ventilation over their heads without direct drafts is best. Using vaseline or other creams and ointments can actually cause more frostbite. Unless they are very swollen and runny, I would let them heal on their own. Most combs that are frostbitten will eventually become smaller and more rounded off. Heating coops is usually not necessary or even safe, since they need to be able to tolerate the cold temperatures outside of the coop. We read here of so many coop fires in winter caused by trying to heat coops with heat lamps, so I discourage that.
