Bees usually overwinter in one hive box. During the spring and summer the colonies grow and thus need more space. Therefore the beekeepers add extra hive boxes, also called supers, so that the colony has enough room for both brood and honey. The added hive boxes usually contain frames; either built combs or wax foundation frames.
The first expansion should be done once bees have filled all the beeways in the first hive body. The expanding is usually done with built combs, but one or two wax foundation frames can be included as well. The drone comb for Varroa control can also be added in at this time. Be aware that in the cold spring weather, the bee colonies are very susceptible to disease outbreaks. So you want to limit the amount of disturbance and you should not give them too much space, since this will make it difficult for them to keep the brood area at the right temperature. To avoid cooling the brood area too much, the expanding can be done underneath the brood area or the added box can be separated with a newspaper that the bees can remove when they want to.
- In South-West Finland, the first expanding is done with a newspaper between the old and new boxes. The new box is given either above or under the existing hive body. When adding a second hive body, the existing hive body will always be inspected from underneath by tilting it up and taking note of how many beeways are occupied. Only if all beeways are occupied in the lower part of the hive body, is a second hive body added. The reason for tilting and checking from underneath, is that this disturbs the bees much less than opening the hive at the top. It is crucial to not disturb the bees during early spring, since at that time there are only very few worker bees per brood cell that have to keep the brood area at 34°C. This is really hard work especially if the surrounding temperature is still quite low.
- In Mid-Sweden, the first expanding is done once the beekeeper counts 7-8 combs with brood in an 8 to 10 frame hive body. Two built combs are added next to the brood area and one or two surplus food frames can be removed usually at the end of April.
- In southern Norway, a box of built but new combs is given to most of the colonies between the last week of March and the two first weeks of May, depending on the weather progression in the respective year.