Re: Grow lights

Pumkinguy@aol.com wrote:
> 
> Chris and rick,
>    It is important to keep the lights close to the plants....a few inches....
> they run cool and will not burn the plant the way a metal halide lights can.
> I had a day long interview about 10 years ago with Chris Mpelkas...
> Photobiologist for GTE Sylvania in Danvers Ma. ( Now Retired). I don't have
> the exact figures in front of me ( I have it written down somewhere) but as I
> recall the intensity of the light source is cut by 50% when you  increase the
> distance from the light to the plant by a foot, in other words, The light
> intensity is X when the lights are very close, 50% X at one foot, 25% X at a
> two foot distance. So if you have your lights 2 feet away from the plants you
> are getting poor quality light. There is nothing like the real sun. Thats why
> it is important to get your plants up quick and out in the real sun when they
> are a week or less old. There is no gain in letting plants get pot bound and
> sitting around in poor quality light.
>                                                        pumkinguy@aol.com
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Actually the light intensity decreases by the SQUARE of the distance, so
the fall off is even more dramatic.  Double the distance and you only
get 1/4 the light.  Triple the distance and you only get 1/9 the light. 
Quadruple the distance and you only get 1/16 the light.  Etc.

-- 
Regards,

Chris Wilbers
Sioux Falls, SD
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