no they don't have to be the same but the wattage for the ballast needs to be the same

If you have a 600 watt HPS ballast, you need a 600 Watt MH Conversion bulb
Revanche21 Reviewed by Revanche21 on . Question about wattage Do you need same wattage per sq foot for veg as you do while flowering? i am thinking of getting a 400W MH for veg then switch to 600W HPS. Question is if I use same space (12 sq ft) is it ok to use the MH for veg even though it is only giving a little over 30 watt/sq foot. I am thinking of growing them about 2 feet then put them into flower. thanks for any help! Rating: 5