Flow is a somewhat confusing term that beekeepers use to indicate that there is enough nectar forage available for bees to not only satisfy their immediate needs but to also store the excess as honey. Flow, Nectar Flow, Honey Flow – they all mean pretty much the same thing.
Sometimes a flow happens in Early September when Goldenrod blooms, and occasionally there is enough good weather in March for the bees to store some maple honey, but here in Cookeville TN our only reliable honey flow is around May 1st when Tulip Poplar and Black Locust trees bloom. In many years both of those highly productive blooms happen at the same time – which is unfortunate because the bees just can’t gather all that nectar at once. Based on my informal survey of trees in my area Black locust is nearly in full bloom right now – April 21, 2017 (suddenly in just the last 2-3 days) but Poplars are not yet in bloom. This is actually good because with a little luck the main flow will last longer than usual.