lighting question

i have read alot of places that you need atleast 100 watts per plant when growing but im not sure how true this.....if i were growing med size (4ft ) plants shouldnt i be able to grow 5 good plants under a 400 watt light or would it b better to stay with 4...????another question is how reliable are the sunsoaker umbrella reflectors??? are they worth using??? thanks for any help

well, i've personally never heard of the 100 watt per plant rule. the most important factor to consider is lumens per square foot. the "magic number" is around 7-10k for some primo buds. also, there is a school of thought that says around 50 watts per square foot for best results. if you plan on growing a lot of plants in a small space, then light penetration becomes a more important issue to consider as well. in this case, a 600 watt light would serve you better than a 400 watt light would. hope this helps!