The time (many weeks after vines emerge from dormancy, usually in May in the northern hemisphere; and in November in the southern hemisphere) when tiny white flowers appear. Vines are hermaphroditic, so the flowers pollinate themselves. Pollinated flowers ultimately become clusters of grapes. Flowering is a delicate process. To happen well, the weather must be calm, the temperatures must be moderate, and there should be no rain, frost, hail, or extreme wind, all of which could knock the fragile flowers off the vine resulting in no grapes. Flowering is happening right now in many vineyards in the U.S.