How Do Flowers Get Their Color?

Flowers grow in every color of the rainbow, providing a natural palette for gardeners and decorators to enjoy. The process through which flowers get their color is grounded in the science of floral pigments, cell structure and light refraction. The flower colors found in nature never were meant to please humans -- that's just a wondrous side effect. They exist to attract pollinators and facilitate reproduction.

All flower colors are produced through pigments that occur in chemicals deep in the cells of the plant. The same color pigments that make leaves change color in fall give color to flowers, vegetables and other plants. These pigments are called anthocyanidins. Individual pigments are named for the flowers in which they first were found; the purple petunidin pigment, for example, was found in the petunia. These pigments show through the cells of the flower blossoms and are refracted, the same way prisms refract light. The prismlike effect creates different shades of blue-green, purplish-blue and other combinations.

Some flowers change colors. Forget-me-nots and lungworts bloom pink, then turn blue over time. The phenomenon occurs when flowers have aged past pollination. Weather and temperature conditions also play a part in flower color, making blooms more or less vivid. Cooler garden climates are more likely to have bright blossoms, while warm summer gardens have deeper, duller flowers. Drought, disease and other problems affect the way pigments are produced, and also may affect flower color. Hydrangeas change color depending upon soil conditions; turn the blossoms from blue to pink by lowering aluminum levels in the soil. Change them from pink to blue by adding aluminum.

In nature, flower colors serve a very important function: attracting pollinators. Flowers produce pollen, a necessary ingredient in their reproductive cycle. Many flowers do not self-pollinate and need insects to transfer pollen from one flower to another so they can develop seeds, which eventually become new plants. Certain insects are drawn to certain flower colors. Butterflies and hummingbirds are drawn to red flowers, while bees gravitate toward yellow blooms.

Scientists genetically engineer plants to create unique color combinations that aren't naturally found in nature. Like people, flowers have genes that determine certain traits, like blossom color. Scientists mix different plant pigments to create colors, injecting them into plants to produce new shades. Through genetic engineering, flowers can be enjoyed in a wide range of colors. Blue roses, for instance, do not grow in nature but can be created in a lab.