most people will tell you low to medium light. I have found that they split faster and multiply more when acclimated to high light, especially those originating out of fla. my friend who propagates at the university keeps his under 250w mh bulbs at a distance of ten to fourteen inches, he has a phenomenal growth record. they can take medium light no problem, IMo if you want them to grow and multiply fast acclimate them to higher light.
what do you have for lights if I may ask?