Spectrum effects which chlorophyll you stimulate like Blue light stimulates Chlorophyll A, which helps the plant develop more leaves and stems. Where as Red light stimulates Chlorophyll B, which helps build flowers.

Intensity is needed! If you were to attempt to grow under say a single 23w CFL. You'd end up with a plant reaching for more light. This would land you a two leaf, 3 foot plant with no nodes. MANY CFLs can help a lot.

You can do 18on/6 off or 24/7 on for Vegetation(growing) and 12/12 to flower.

I'm in the middle of a trial grow just to get some hands on experience. I popped the seeds under little more then a single CFL. However I've been adding extras ever since. Many people use CFLs. Just go to basic growing and look in the grow log area. You can see many CFL grows and if you look hard enough you can find examples of people who tried to grow under a single bulb.

Here's a link to a couple CFl grows including my trial grow:

http://boards.cannabis.com/grow-log/...rial-grow.html

http://boards.cannabis.com/grow-log/...-cfl-grow.html