DS bulbs offer both red and blue light spectrums. This means you can use them in both vegetative and flowering stages of plant development. This is a great bulb choice for beginners using artificial lighting and is more affordable than having to buy both MH and HPS lighting. For optimal yields, we recommend going with both an MH and HPS setup. This change in spectrum, from vegetative to flowering, will optimize your yield and closer mimic the natural changes in seasons.