Beekeepers who put their bees in on or around April 11th should be very close to adding their second box. When the bees have drawn out or working on 8 of the 10 frames in the box, it is time to add a second box.
A frame that the bees are working on, with nectar and pollen in the frame, not brood, is moved from the first box and placed into the center of second box. This frame is bait for the bees to move up.
There now are 9 frames in the first box. Evenly space them out and run 9 frames in the bottom box.
If the bees have not drawn out 8 frames yet. Sometimes the bees will not expand their comb building without a little help. When inspecting the hive, start pulling frames from outside frames and moving towards the middle frames. The first frame that you come to, the bees may be working on one side and not the other. There will mostly be nectar and pollen on this frame. Turn this frame around and put it back where the frame was. The bees will start working on the new side. Do this on both sides of the hive.
The next week if the bees are working on both side of that frame and have not moved to the next outside frame, you move the frame of nectar and pollen out one frame and put a new frame into the place that the nectar and pollen frame was. This helps the bees expand their brood nest.
When the second box is added, the entrance reducer is increased to the bigger opening.
Remember if you are drawing new foundation, you need to feed syrup until mid June. If you are not feeding, the bees will not expand their brood area and the population of the hive will suffer.