On my 300w led light do i use both veg and bloom s...

hi there.. bloom should only be used during the blooming phase, so i would start out with only veg.. also be sure to keep the distance quite high (or dim it down) so the light intensity isn't too strong, as seedlings are still very sensitive to bright lights.. just raise the intensity (or lower the light if you don't have a dimmer) gradually. The bloom switch should be engaged, once blooming has started and the energy is being used for creating buds. happy growing!