While you can use HPS, you'll find MH to be much better suited for vegetative. The 'cooler' wavelengths of the MH keep the plant from stretching as much, keeping it shorter and bushier. The 'warmer' wavelengths of the HPS are better for flowering because that is what helps trigger the budding.
gainesvillegreen Reviewed by gainesvillegreen 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