What is the importance of colors in the novel, This Poison Heart?

Colors are often symbolic, and many of the colors in this novel have symbolism related to plants. After Bri has been working in the herb garden for a while, she notes the many shades of green of the various plants growing there. The green symbolizes life and rebirth. As a contrast, the Poison Garden is filled with shades of black and gray, which symbolize darkness, danger, and death. One of the plants in the Poison Garden is covered with crimson thorns. Crimson, a shade of red, symbolizes blood.