Yes, color does affect plant growth. Colors are simply different wavelengths of light that are reflected by objects back. For example, plants look green because they have a lot of chloroplast in them, which absorbs all visible wavelengths of light except green, so leaves look green to us.

Different colors are associated with encouraging different parts of plants to grow. Blue light will allow the plant to grow leaves and other vegetation and red light with blue allows the plant to grow flowers. The plant does not absorb the green light so does not use it to grow.

The color or wavelength of light does affect photosynthesis, which is how plants can basically create their own food. Essentially, the reason why plants are green is they are absorbing the other wavelengths of light but reflecting back the green. The wikipedia page on photosynthesis goes into a lot more detail. Here is a short page about the different absorption spectra of light for different pigments in plants. .

One of the professors at UCSB told his little sister to do a science fair project, growing plants under different colors of cellophane sheets. Different colors of light came through the cellophane sheets of different colors, onto the plants. She won a prize for her project.

Plants do respond differently to different colors of light being shone on them, because chlorophyll reflects green light and absorbs blue and red (therefore, blue and red are useful for photosynthesis, but green isn't).