All colors of light matter, thus there isn’t one that is better than the others. Nevertheless, gardeners may use grow lights that emit more of a single color of light.
For instance, in large commercial applications where they are aiming for specific results and high yields, they alternate between lights that are heavier in either red or blue light depending on where their plants are in the growing cycle. To be exact, in the vegetative phase, plants that receive sufficient blue light will be robust and healthy. On the other hand, in the flowing and fruiting phase, red light is ideal for promoting budding and fruiting
However, for the majority of small-scale, domestic applications, such as those involving houseplants, the ideal grow light should cover the entire PAR spectrum.