I think your plant will tell you how many lights it needs as it grows. IF you are paying attention. As it gets bigger, you will need to get more lights to cover it. The bigger it gets the more light it will want. Start small and grow with the plant. Try to get the maximum LUMENS and keep them close to your plant. VERY CLOSE! Good luck!
I started with 10 plants and 80 watts, now I have 6 flowering females under (and next to) 850watts! Didn't plan it that way, but thats what happened. And I did NOT spend much money at all.