too much space for that light. you want about 50w of light per square foot. so under optimum conditions, a 400w lamp will only cover about 8 sqft. though they will all grow under that lamp, you just can't make the most out of your space that way.
basementbotany Reviewed by basementbotany on . Maximum Area for a 400W HPS Light I plan on having about 20 plants flowering at all times in a SOG style perpetual harvest with a 400W HPS. What would be an ideal size enclosure for this grow light, space is not an issue i just need the best dimensions for this size light and plants. I was thinking a 4x4 square flower cab with another about the same dimensions for mother/clone vegging with just cfl's. Rating: 5