What are the motifs in Blue Is for Nightmares by Laurie Faria Stolarz?

Witchcraft is a recurring idea in urban fantasy. Such theme allows to build a world that is unique, where different rules apply. We also need to be familiar with the way this world works. Stacey has to know the meaning of lilies to prevent her friend's death. It is only through the knowledge of this world, where she gets to know the meaning of colours, flowers, and spells that she is able to survive. If she would ignore the meaning contained in lilies she would not try to have more dreams about the future and warn others.