colortemp_chart1.jpgcolortemp_chart2.jpgcolortemp_chart3.jpghortgraph2.gifcolortemp_chart4.jpg
The diagrams above shows the full range of light and where each type of lighting system falls within that range. Artificial lights produce just a slice of the full range. This leads to much discussion and experimentation to determine which, or which combination of lighting is best for a particular crop.
Lets establish a reference point to work from, examine several types of lighting and put this information to practical use.
Reference point: For most of the daylight hours, the outside daylight peak is centered on 5500 degrees Kelvin (refer to the above chart).
Metal Halide: These lights emit a light on the bluish side of the spectrum. They are considered a grow light and it is considered that they produce a more stalky vegetative type of growth in plants. These lights are commonly used throughout all phases of plant growth and produce excellent results.
Agro Sun Halide: Agro Sun is a hybrid halide bulb that generates extra red light for flower and fruit production.
Sodium Vapor: Sodium vapor lighting is way down in the red. There is some indication that the spectrum produced by these lights promote flowering.
Thanks to ik3002 for extra info!