Space

A colony's box is not a permanent home, it is a container that gets outgrown. As soon as the existing box is roughly seventy to eighty percent full of bees and stores, add room ahead of the need rather than after it, commonly before the main flow gets going in earnest.

A colony that fills its box does not simply stop growing and wait patiently, it starts backfilling incoming nectar into cells the queen would otherwise use for eggs, which squeezes her laying space further still.

Crowding is also the single biggest trigger for swarming: workers rear new queens, and the old queen leaves with roughly half the population, taking a season's worth of momentum with her.