On Wed, 09 Feb 2005 12:58:31 -0500, Ralph D. wrote:

So... as a carry over from the other thread...

Another thing the agent thought was that I had made a mistake in
swithching to all grow lights. Says that they are not full spectrum and
suggested adding a few regular flourescent lights. I have 5 shelves with 4
'Grow Stick' flourescent lights. If I were to place a small lamp on the
top shelf and another on the middle shelf with those newer screw in type
flourexcent bulbs meant to replace traditional bulbs at 26Watts each
(maybe three lamps?) would this add a sufficient amount of the missing
light? I have no convenient way of getting them to a good window and start
waaaaaayyyyyyyyyyy too many seeds for window sills (not to mention old
aluminum frames transmit the cold at night and there would be a PIA ritual
of taking everything down and putting it back up again in the AM).
Anybody know anything about light spectrums as it would relate to growing
seeds?


Seeds require little light (or no light) to germinate. Heat is generally
more important for germination.

Lights in a nutshell...
I worked at a factory greenhouse (Smith gardens slave factory) and while
there I was working with the light guys. I've played with a lot of
commercial lighting systems over time and light specturm was talked about
alot. Lighting systems break down to three types: High pressure sodium,
metal halide and fluorescent.

High pressure sodium or HPS systems produce an orange/red colored light.
These are most commonly seen in use as street lights. The light spectrum
produced is red-far red as plants are concerned. This is the better light
spectrum for producing flowers and fruits.

Metal Halide systems are the most efficient 'white' light producing light
known to man. These are most commonly seen in warehouses and stores. These
lights produce a blue-blue white spectrum that work best for folage plants
or non-blooming/non-fruiting plants.

Fluorescent systems varied as far as their out puts and spectums. The cool
white/ shop light types produce a blue spectrum, while the kitchen and
bath lights produce a red/ red'ish spectrum. For starting seeds or
vegetating plants, a blue light should be just fine. To help encourage
those little african violets to bloom, a deeper red spectrum light would
be used.
I tend to cheat and encourage my clients who use their lights for seeding
and growing to mix the lights. A cool white and a kitchen and bath in the
same light fixture will produce a near full spectrum, generally at a
cheaper cost to the full spectrum plant lights.

A word to the wise..., mercury vapor lights do not produce a useable light
to plants. The light produced is too far into the blue spectrum and the
majority of the light engery is just plain wasted. If you find yourself
using lights more often than not for your house plants and garden plants,
it's well worth the money to purchase a metal halide or hps light fixture.

Happy gardening .

--
Yard Works Gardening Co.
http://www.ywgc.com