Grow Lights

From: Zachary Kaufman (
Date: Tue Jun 01 1999 - 11:57:22 PDT

Date: Tue, 01 Jun 1999 11:57:22 PDT
From: "Zachary Kaufman" <>
Message-Id: <aabcdefg1937$foo@default>
Subject: Grow Lights

This was my response to a post last week. Unfortunately, there was
a problem with the address, so I'm re-posting it now.

I've heard things on this subject a bit differently. Cool white lights
have more [relative to?] blue in their spectral output. Warm white
have more [relative to?] red in their spectral output. Chlorophyll
is "stimulated" the most efficiently in the blue and red spectrums.
Inducing flowering in many plants requires light in the red spectrum.
Flourescent growlights come in two varieties--those that try to mimick
the sun's spectral balance [full spectrum lights] and those that try
to maximize growth and/or flowering by sacrificing overall intensity
for spectral output in the blue and/or red regions.

Feel free to correct on any of this anyone [aside from spelling ;-)].

It was written:
The main difference is the spectral composition of the different
lights. The cool and warm whites are more in the blue range, the grow
lights emit in both the blue and red ranges. The blue isused primarily
for growth, the red for flowering. That's why you
sometimes find fluorescent fixutures designed for growing plants
also have a space for an incandescent light which is very rich in red.
I use a combination of cool and grow lights,
and the plants seem happy!

Happy growing,

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