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Plants per Square foot?

Discussion in 'Indoor Growing' started by Donkeydude, Mar 14, 2008.


    Donkeydude Active Member

    I recently received a 400W HPS light and am combining it with my friend's 400W HPS light for a larger yield. My question is: how many plants can we grow with this much wattage? Theoretically, each light should be able to cover about 16 square feet, but I'm not sure how many plants will fit in each square foot before they start blocking out light that should be going to the other plants. Just for reference, the strain that we're using isn't very dense, but does grow up rather tall.

    I guess the essence of the question is, how many plants can we grow with 2 400W HPS lights?

    Sikk Active Member

    I have 2-400w mh and 1-1000w hps i use 2-400w mh for 10 plants is good for 5'x5' now my 1000w hps for 12/12 same place 5'x5' ok and my plants grow up to 5' to 6' feet is ready for 12/12 for good yield :joint:

    Roullette Well-Known Member

    Recommended area coverage for a 400 Watt HPS bulb is 5'x5' and can be used in a 8'x8' area. so depending on how you set up your lighting you can actually light a 10'x10' area with best results from the HPS. you just have to space your plants out as they grow which depends if your strain gets bushy. since HPS has such a high red spectrum it has a good amount of "far-red" lighting. Far-red lighting is a light that is "seen" by the plant but not absorbed its reflected. As the plants reflect that they notice more far-red spectrum and kick them selfs in to grow mode basically a race for light. so the more plants you have the bigger they will grow (this is a scientific study). but you just want to have enough plants that if they grow bushy there not going to out grow there 10'x10' area. so basically depending on strain you can fit a good amount of plants. an exact number im not sure

    rice420 Active Member

    Got a grow tent 3ft x 1 1/2ft x 5ft ... Trying to fit an air cooled vent with 400 watt HPS/ MH conversion bulb. Is this too much for this size of grow space im working with. Let me restate that in that i know too much light cant be bad, but well the heat generated get too hot for that small of space?
    Jah Bless

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