Someone correct me if I'm wrong, but I believe HPS is the incorrect wavelength/kelvin so I don't think you can use it for veg...

[Edit] My bad I just saw this thread http://boards.cannabis.com/indoor-li...6-hps-veg.html and according to people there, you should be OK.
Backpacker420 Reviewed by Backpacker420 on . metal halide question is there a HUGE difference in growth if you use a metal halide to veg rather than a hps? Rating: 5