Pollen varies in quality
Here’s a selection of pollens gathered by bees in southern England in May 2020.
The yellow is oilseed rape (canola).
Brick red is horse chestnut.
Blue is phacelia (grown for game birds).
That’s quite a selection, but all pollen isn’t of the same quality. And it does deteriorate over time.
But whatever the season there is sustenance for bees from Vita: