Woo-hoo! I had 3 hives left going into winter and swore that if I couldn't get them to winter over, I was calling it quits. I left plenty of honey on them and didn't feed syrup, and in early February I did what has been suggested by others, and put a 15 watt bulb in each. It was humorous to walk through the backyard in the dead cld of winter and see the glow coming from the little entrances. But wouldn't you know? Now that the weather is turning, these hives are buzzing like crazy! Even in good years, I've never had over-wintered hives this strong so early in the season. The maples and pears and forsythia are in full bloom, and I wonder what kind of honey they make. :? Yeah, I'm putting more supers on this week to start building up the crop.
The past few years, in the weird late winters and springs with the frequent warm spells and cold snaps, I've lost so many hives due to them trying to keep brood warm when the weather turns bad. Even with lots of food left in the hive. I think these little bulbs have been the single cost effective tool to get the hives through winter. Besides making sure they got enough to eat.