A Metal Halide bulb in the 5000k-6500K.. kelvin, color temp range will reduce the stretching of plants.
A HPS bulb will let the plants stretch more, but is fine for vegging too. Most HPS bulbs are in the 2000k-2700k...kelvin, color temp range.

I've used both... use, whatever is easiest, for your situation...the KISS principle...:thumbsup:

I use 6500k High Output T-5's, now...for vegging
Dutch Pimp Reviewed by Dutch Pimp on . Should I use MH at veg and HPS during flowering? Hey just a basic question to the pro's, should I use MH during vegetative growth period, and switch to HPS when flowering period starts? Or should I just use the HPS throughout the entire growth cycles, since there is max output with that? I was also looking in to a LED setup but not quite sure if it covers all aspects of needed lighting. Any and all help is appreciated! Rating: 5