need a light just for flowering

600 w hps should work for that space.

a 600w could not cover this area in flowering, it can cover 3x4. IMO since the shape of area is 3x6 you will have better light spreading if you get 2 lights 400+600 or just shrink the area to 3x4 and go with only 600...

A 600w HPS covers approx. 1 square yard or meter (3x4) I do 9 plants in 3 gal pots to 3ft high in 3 months, consider the extra room as airing ...!

Here's a list of coverage you can find listed 100 times on the internet

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  • • 100 watt lights: 1.5FT x 1.5FT growing area
    • 150/175 watt lights: 2FT x 2FT growing area
    • 250 watt lights: 3FT x 3FT growing area
    • 400 watt lights: 5FT x 5FT growing area
    • 600 watt lights: 6FT x 6FT growing area
    • 1000 watt lights: 8FT x 8FT growing area
  
  
  
  

A lot depends on the reflector, which nobody mentioned. Or bare bulb even? I got a 600 in a 5 X 5 and it does good with some supplimental cfls.

Anyway you'll get more from under a 600 in a 5X5, than a 3X4 no matter how you work it, assuming you got your plants trained to make full use of your grow area.

Or consider a 1000 dimmable, not much more.

Thanks guys for the replies! AimAim what should I be looking for in a reflector/bulb if I go with 600/1000? My room is wrapped in mylar and I have been training the plants , the biggest one is maybe 2ft but has 8 large colas all plants r in 3 gallon pots.

are you saying that my 400w can cover 5x5? theres no way it can no matter what the reflector, no matter if it's listed 1000x, a 400 will not cover 5x5... IMO

in a 3x6, id do 2 400s barebulb vertical, you got 7ft of height, dont waste your money on dump reflectors. spend the money from the reflectors on a window or portable AC and grow a lot more green then you would with any hood setup.

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xoxx0x Run it just like that. Massive Yields. x= plants, 0=lights
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Or split it in half and do 2 stacked 400s throw a shelf around the 3x3 and have 2 levels of lights. turn the onther 3x3 into a veg cab.