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 of explaining grow lights and options
http://www.littlegreenhouse.co...
