When purchasing your grow light, it's vital that you do your research on the system's output before you finalize your purchase. Red LEDs stimulate flowering and fruiting in your seedlings, and it also mimics the shorter days of the season, allowing you to put your plants into the flowering phase of its lifecycle. Therefore, red light is essential for growth, but it shouldn't be overwhelming in your grow light. Blue light LEDs assist with the vegetative growth of your plants. It's the ideal spectrum for seedlings, but you do need to include some red light to balance it out.