there is a thread that jon started few days ago. he is talking about similar thing. giving partial sun light to possibly promote better rooting process. my cuttings don't stay in total darkness, but at the same time, the amount of light they are getting doesn't amount to much. too things i notice are more important to rooting than light at initial stage. moisture control, and temp. too cold, it won't root. too hot, it will dry or rot depends on the moisture level. if the moisture is too much, it will rot or mold. too little moisture, the will dry out.