[Wolfie]

HPS lamps are not as monochromatic as LPS, but they are still highly slanted to the yellow / orange end of the spectrum and are not good for plant growth.

The yellow/orange end of the spectrum is exactly what is conducive to better flowering of the plants. Savvy growers use MH during the vegetative state, then switch to HPS (along with changing the photoperiod from 24 hours on to 12 on/12 off)for the flowering stage.

[Vigilantcitizen]

"The yellow/orange end of the spectrum is exactly what is conducive to better flowering of the plants. Savvy growers use MH during the vegetative state, then switch to HPS (along with changing the photoperiod from 24 hours on to 12 on/12 off)for the flowering stage."

I concur.