In the Democratic People's Republic of Oklahoma, dandelions bloom year round, but spotty. They will not help my bees much. I do understand as you go up north, they are becoming a major pollen source. Ironically, (one of my students said "Irony" is an adjectival form of the noun "iron" [pronounced as "arn" around here]) the further north you go, the longer the nectar flow. For instance, Canada produces more honey than USA. Go figure. So overall, considering this give and take, things are fair in the global village, I guess.