Flowers come in various shapes and colors. However, they do not randomly choose their colors. Surprisingly enough, there is actually a reason why "roses are red and violets are blue". In other words, nature has its own purpose. Here, this purpose is evolution.  

Flowers have certain pigments because these pigments give them an evolutionary advantage. Walking and observing wild flowers in the DMZ, I learned that there is a relationship between flowers and their colors. Most flowers in the wild do not have primary colors. Instead they have pastel tone colors. Flowers that have strong, intense colors are garden flowers which humans have manipulated to have those colors.

Flowers are the instrument with which the plant spread seeds and bear fruit. So, they must avoid being eaten by predators. Flowers tend to have softer colors so they can blend into their surroundings better. The flowers should not attract predators. In contrast, many of the fruits we know have primary colors. Apples are red, bananas are yellow and blueberries are blue. Why is it that so? Fruits, unlike flowers, must attract animals. (This principle do not apply to all flowers and fruits)

One characteristic apart from color that is common among flowers is that they are dispersed around the ecosystem. Flowers do not exist as colonies. Rather they grow separately as individuals or small groups. A population would be more vulnerable to extinction if the flowers are concentrated. They could be eaten to a predator as a whole and also, disease can spread around much faster.