6,000 lumens. Dont know if ya know or not, so here goes...

A lumen is the measurement of light that a bulb gives off.

Simple lol. You can have 5 CFLs to give off 6,000 lumens, or you can have 10. It depends on the wattage that they are. When buying them, its important to look for the ACTUAL WATTAGE/OUTPUT, not the output that an incandescent bulb of the same wattage will give off. In other words, look for the SMALLER number and go from there. For a successful CFL grow, you want to start with between 150 to 200 watts, then slowly increase that as you get nearer to the flowering stage. In the end you ideally want to have about 350 watts, if not more. A couple of advantages with CFLs is that they hardly give off any heat, are cheap and readily available, and they can be placed anywhere you want them around the plant. This means that even the small 'popcorn buds' at the bottom of the plant will be bigger and more compact than if growing with a HPS (High Pressure Sodium) bulb.
Dont let what Ive said put you off the CFL idea though - if you cant get more than 200 watts of light, then youll still do fine. Just make sure to flower a bit earlier than you should, and be prepared to possibly wait a little longer for her to mature and have a slight decrease in yield. BobBong has an excellent thread in the Indoor Growing section where he uses CFLs and uses heavy LST - thats basically tying the plant down so it resembles a small bush - so the light can get to the whole of the plant, and he had a very respectable harvest.