What does it mean if you dream of a blue hyacinth?

A single image out of the context of the whole dream does not have any particular significance. The meaning lies in the emotions you felt in the dream. For example, perhaps you were feeling "blue," that is, sad and lonely.

> On the other hand, if the question refers to a blue hyacinth Macaw, the dream might have the opposite meaning, picturing the Blue Bird of Happiness.