What Ed Rosenthal Said

From Ed Rosenthal: (I spun his message to avoid plagiarism banishment) 
 In the new Skunk Magazine there was a question in the "Ask Ed" section That I thought was worth posting here for people thinking about using CFL's or HID's for a stealth grow room. . . .

The Asked Question Was: I intend to grow a single cannabis plant in a space
1' x 2'. What light would you recommend? I was think of using four 30-watt compact fluorescent lamps. Will this be enough? Cost isn't an issue but I am deterred from getting a high pressure sodium light because of the amount of heat the bulb produces.

 The Answer Is: As you mentioned, you have several lighting systems to choose from, including compact fluorescent s and high pressure sodium (HPS) lamps. Among HPS lamps you have a choice between a single 100-watt lamp which uses a total of about 120-watts and emits about 8,800 lumen (73 lumen  per watt) or a 150-watt lamp, which uses about 180 watts and emits almost double that-15,800 lumen (87 lumen per watt).
 A 42-watt compact fluorescent (CFL) emits about 2700 lumen (64 lumen per watt). Four 42 watt CFLs use 168 watts and emit 10,800 lumen. Other size CFLs have a similar efficiency, however, that is only part of the story.
 Marijuana plants use mostly all red and blue light. Green and yellow light is of little to no use to them, so light or lumen that is put out in these color spectrum’s is totally wasted energy. Pretty much all of the light emitted by HPS growing lamps is in the yellow color spectrum or kelvin. Only a small amount of the light put out by them is in the red or orange color spectrum’s, that plants use efficiently and thrive on. Meanwhile, warm white CFL's bulbs (2700 Kelvin) emit a greater portion of their lumen in the red and orange kelvin sectors.

 Although CFL bulbs produce only about 75% of the light per watt that the HPS does, the amount of light usable by the plant is at least equal or higher with the fluorescents or CFL grow lights. You might want to experiment your self to see if adding just one cool white (6500k) CFL to replace one warm white results in shorter, stouter stems and more vigorous bud growth in bloom. The reason this is that warm whites (2,100 – 2,700k) don't emit hardly any blue light, which the plants need to regulate their growth and for photosynthesis. Having just one cool white bulb supplies the blue light needed in bloom.
  My advice for your grow space would be to use several (three to five) CFL's bulbs with a combined input of around 120-160 watts. Even though the 150 watt HPS grow light is slightly more efficient that the CFLs grow light in total lumen output, watt for wattage the compact fluorescents provide as much useful light as the HPS grow lamp.

  Heat is also another factor to consider. Consider that a HPS grow unit will run much hotter and emit more heat than the flourescents ever will. Make sure your using good reflective material around & in the garden so that any excess light trying to escape the garden will be reflected back to your plants. Any light that doesn't get to your plants leaves is completely wasted.


 http://stealthgrowlights.com