I do not like using a calender, because the bees don't seem to either. What is blooming sometimes is better, but then the weather factor... When the dandelions and fruit trees are finished, things start to heat up. If the basswoods are blooming, you are getting safe. Some where in between is the danger zone. I know, not much help. Watch your own hives and see when they start to set cells.
Sorry
Roland
Sorry
Roland