Laurence Edwards explains why UK beekeepers should place the brood box underneath in spring. When weather swings from warm sun to snow, brood underneath keeps the colony insulated and safer from cold snaps. A brood box on top creates an empty void that traps heat and leaves bees vulnerable to sudden freezes.
If you double brooded your colonies underneath last week when it was sunny and you're looking outside today and it's snowing, you have set your bees up perfectly to cope with this snow. If you double brooded and you put your brood box on top, separated the bees from the feeder, and given them a big empty void in which all of that heat's going to rise up, you might be in trouble today, and I would reevaluate that decision for next year. Double brooding underneath is the way forward in the UK when it's 24 degrees one day, snowing the next day.
