I am not very knowledgeable on live plants, but I believe for high light plants you need at least 2 watts per gallon. But hopefully someone more knowledgable than me (which would be just about anyone) will give a better answer.
It used to be linked to through our site but I couldn't find that thread, so I just lifted this from Google. I hope that's okay
Note that the length and wattage of the bulb aren't even mentioned, because the more important thing is the type of bulb. Unfortunately CFLs aren't listed because their PAR data (information about the light that plants have available to them, under a certain bulb) is harder to gather/more complicated to interpret because of a number of factors. At least, that's my understanding.
I'll also throw in that if you're looking at bulbs with ratings on them, I believe the range for plants is 6,500K to 10,000K daylight rating. If that range is wrong I'm sure someone will correct me.