The answer is: use honey super, or candy board. During the early spring, when the bee colony is the smallest, it is very hard to collect new energy sources and feed the brood. In that time also many bees die by age and cold. If the colony is small and without sufficient sources, the queen lies less eggs per day and the reconstruction of the colony is even slower. It may take longer than the surrounding nature starts to flower and produce maximum of nectar flow.
Therefore, candy board can speed-up the colony development. It is a simple frame with a net, where we put the mixture of a sugar and honey. The board will be stored on the top of the hive during next warmer days.