Plants reflect the colors of light that they do not absorb. This reflected light determines their color. Why are there few blue-colored plants?

Plants have lots of blue pigments.

Plants absorb blue light well.

Plants are not usually exposed to blue light.

Plants reflect most blue light.

The answer is: Plants reflect most blue light.

Plant color depends on the color of light they reflect and not on the color they absorb. For example, a green plant is green because its pigment chlorophyll absorbs red and blue light, and reflects green light. So, if some plant is blue-colored, that suggests that it reflects blue light.