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Propagation: Both ends of the (light) spectrum

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Forum: PropagationReplies: 5, Views: 59
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Bolivar, OH

February 24, 2010
1:43 PM

Post #7583862

I purchased a new grow light yesterday. When I got it home and hooked it up, I discovered that the light is much more toward the red end of the spectrum than the other lights that I already had. Now I'm wondering if one is better than the other for seed germination. I am germinating peppers, tomatoes and Amaranthus caudatus right now - under the warm spectrum light. I have coleus, basil, Verbena bonariensis and Nicandra seedlings growing under the cool spectrum lights. Am I good with leaving things where they are or should I switch anything around? I have always germinated everything in a south-facing window in the past so I am still trying to figure out the ins and outs of using lights.


Pueblo, CO
(Zone 5b)

February 24, 2010
1:48 PM

Post #7583880

Hear is what I heard:
The cheaper blue lights are actually better for germination, and good enough for young seedlings.
The more expensive red ones are better for long term growth and house plants.

February 24, 2010
3:59 PM

Post #7584192

Some seed germination is actually inhibited by red light e.g. lettuce seeds.
The info on this seems to be in some of the more academic research journals
which I do not have access to.
Calgary, AB
(Zone 3a)

February 24, 2010
4:14 PM

Post #7584236

This is what is in The New Seed-Starters Handbook by Nancy Bubel

"Breaking Dormancy

Light. Subjecting the seeds to light-even a dim continuous light or sudden bright photoflash-will sometimes help, especially with lettuce. Germination depends on total amount received. The dimmer the light, the longer the necessary exposure.

Red Light. Exposure of some seeds to red light (660 nanometers) promotes seed germination. Experiments with lettuce bear this out. However, far-red light (730) nanometers) has been found to inhibit seed germination. Practically speaking, this means that seeds that are difficult to germinate will often do better under fluorescent plant lights. Some seeds won't germinate when shaded by leaf cover, probably because the leaves filter out helpful rays while allowing the inhibiting far-red light to reach the seeds."

In addition, these guys do an excellent job explaining grow lights & options

This message was edited Feb 24, 2010 9:24 AM
Bolivar, OH

February 24, 2010
6:44 PM

Post #7584615


Thanks for the info and the link! Little greenhouse was a good place to compare the different types of lights.

thanks to everyone else, too! I'm gonna take the 'wait and see' approach. If I'm not happy with my germination within about a week, I'll switch some things around.
Fairbanks, AK

March 6, 2010
3:43 PM

Post #7609209

I garden in Fairbanks Alaska, so I have to start all of my plants inside under lights. I use just plain old inexpensive lights with no problems. If I was planning on keeping plants under lights for their complete life cycle I would consider more expensive grow light bulbs

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