Only young sunflowers follow the sun. They lean west through the afternoon, then swing back east in the dark so they’re already facing the right way before it rises. Once they flower they stop, and nearly every head settles facing east for good. The east-facing ones warm up sooner in the morning, and bees visit them about five times as often as heads turned west. So the grown plant doesn’t chase the light any more. It waits where the light is going to come from.