400 watt lamp

I don’t know the height at which I should set my 400 watt HPS light and in how big of an area should I enclose it.

Set the light about 12 inches from the top of the plant canopy. For the vegetative stage the light can be used to cover about 16 square feet, a 4 foot x 4 foot area. For flowering, the plants should have light in the range of 40-80 watts per square foot. A 400 watt lamp covers 5-10 square feet.

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