Re: Which type of light doesn't contain a blue spectrum and where can i find it

There are several answers in the madsci archive on experiments that compare
plant growth under different light sources and different colors of light.
Experiments with different colors of light are difficult for students because
expensive equipment is required to assure you are providing the same amount of
light of each color. 

I'm not sure what you mean by "normal light." I assume it is an electric light
source such as cool white fluorescent. Standard incandescent light bulbs have
very little blue light, but are not very good for plant growth because they
produce a small amount of light and cannot be too close to the plants because of
the heat they produce. 

For the experiment you describe, comparing plant growth under sunlight and two
kinds of electric light, you might try cool white fluorecent lamps and Gro-Lux
fluorecent lamps. Gro-lux and similar brands are sold specifically for plant
growth but are much more expensive than cool white fluorescent. You could
determine if they are worth the extra cost.

The fast plant website has directions for making light banks for plant growth.

References


Re: I am doing a project on the effects of colored lights on bean sprouts


Re: Do different colors of light affect the growing rate/ability of plants?


Re: I am doing an experiment growing marigolds under colored light. 


Re: How/why do colored lights affect the growth of plants?


Fast Plants lighting systems