Manual Growing lights
9, it is also important to make sure that the bumblebee hives catch direct daylight
(no filters, screens, etc.). If you do have screens in your greenhouse [...] can happen that the direction of the sunbeams is too low and
therefore doesn’t reach your bumblebee hives if they are behind a sidewall screen (see figure [...] unless additional pollen is fed to the bees.
2.1 When to open and close the hives
In general, the hives can be opened if there is 28 watt/m 2 PAR-light,