Nature has devised several ways to give flowers (and birds) colors! The most common way flowers get their colors is by pigments in the leaves called anthocyanins. "ánthos" in greek means flower and "cyanó" is the same as the color cyan! They are water-soluble pigments without taste nor odor and they come in a variety of colors. Not only do they exist in the flowers, but also in the leaves and fruits. For example, açai and raspberries have tons of anthocyanins. They also give leaves really nice colors yellow, orange and red during foliage. In California we don't have much of a foliage, but if you travel to New England in October / November the tree colors are wonderful.

So, how do they work? It all comes down to what is called the absorbance spectrum. If you have seen a rainbow, then you know that white color we see all around us is composed of all colors, from blue to green to yellow, orange and red (in this order). The job of pigments is to absorb some colors so we can see the remaining ones. For example, chlorophyll absorbs blue and red, so only the green is left for us to see.

Typical anthocyanins absorb a bit of the blue and most of the green, so we can see a lot of the red and yellow. This is why the leaves of the trees in foliage appear yellow-orange-red, and not blue!

Last and very interesting thing about anthocyanins is that they respond different to different pH, for example they respond differently when exposed to lemon juice versus water. So, that becomes really beautiful when the same plant can change colors depending whether it's morning or afternoon, like the plant ​"Japanese morning glory" does, by changing the pH of it's own petals.

But, there are other ways to get color: carrots are orange because of carotenoids; green color in the stems and leaves come from chlorophyll; and cactuses and beet has betalains.

Nature has come up with some many colorful molecules! Some of which now we use for food coloring, and in the old days, some of them they used as dyes for clothes.

You can also look at this older answer from ScienceLine which talks more about genetics and coloring!

Flower colors are caused by chemicals called pigments that plants produce to make their flowers colored. The yellow and orange pigments are usually a kind of chemical called carotenoids, while the blue and red pigments are anthocyanins.

The color you see when you look at a flower is because of molecules called pigments. Pigments are in lots of living things and they give them color. An example in humans is melanin which is what gives human skin and hair its color. When the light hits the pigments, they send out light which we see as color. To make the pigment, the plant first makes sugars from sunlight and carbon dioxide. It can then use the sugars as an ingredient to make the pigment molecules.

Flowers get their colors from things called pigments. We have pigments in our skin that makes our skin darker. Flowers have all kinds of different pigments for different colors. Flower color is very important for attracting pollinators to move pollen from one flower to another. Red flowers are oftern pollinated by birds while blue flowers tend to be pollinated by bees and butterflies. White flowers actually lack pigments altogether.