[permaculture] Fwd: Overdriving Fluorescent Lights

Lawrence F. London, Jr. lflj at bellsouth.net
Thu Mar 3 10:27:19 EST 2011


-------- Original Message --------
Subject: Overdriving Fluorescent Lights
From: Thamnophis <thamnophis at gmail.com>

I think all this discussion of lights and lighting for propagation is
interesting and helpful. I wanted to mention something that most of
you know already - that plants can only use a percent of the spectrum
- known as Photosynthetically active radiation (PAR) - so when
considering lighting its important not how bright a light is to your
eyes, but how "bright" it appears to the plant.

So (as I understand it) a 100 watt light that produces x number of
lumens with a color temp of, say, 6500k may be much more beneficial to
a seedling than a 100 watt light of the same brightness that has a
color temp of 3500k. (K=Kelvin, a measure of the color temperature).
On the other hand, a blooming plant will benefit from a different
color temperature - one more like the red light of summer rather than
the blue-green light of spring.

More info on PAR see:
http://en.wikipedia.org/wiki/Photosynthetically_active_radiation

The other thing I think I mentioned before is that you can greatly
increase the amount of light produced by a regular 4 ft shop light by
over-driving the lamps. Installing an additional ballast is not very
difficult nor expensive but can boost light output by 70%.

An additional ballast might cost $12-$15 and will shorten the life of
the bulbs but might be worth the cost and effort if your trying to
produce stout, sturdy plants. I've done this with peppers and they
grew wider than they were tall with big, very dark green leaves.

A "how to" is here: http://reocities.com/heartland/pines/7557/overdrv1.html

Joe
Boone, IA
5a




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