A popular flower that generally grows in big ball-shaped clusters are often given on 4th Wedding Anniversaries as they symbolize appreciation and heartfelt emotion. They are typically found in white, blue, green, pink and purple. Pink hydrangeas symbolize heartfelt emotion. Blue hydrangeas symbolize frigidity and apology. White hydrangeas symbolize boasting or bragging. Purple hydrangeas symbolize a desire to deeply understand someone. By themselves or in a mixed arrangement, Hydrangea will add meaning and fullness.