Why is it that the marigolds "don't make sense"?

The marigolds are used to symbolize life and happiness. They don't fit into the mood of the place they live. The marigolds don't make sense because they are too pretty and too perfect to be in an atmosphere where she doesn't feel joyous in. In lizabeths eyes, she believes the marigolds are the enemy. It is truly her negative outlook towards her lowly life.