I concur with Son of Hobs,
But remember, Lights are just one part of the equation, you also need to think about fresh air from a screened intake, tent airflow, filtered extraction, type of medium, nutrients, hand or auto watered, etc.
But regarding lights... 4 plants under one Lumatek Digital Dimmable Ballast pro system 6oo watts at 400 volts, with a Dual Spectrum enhanced Lumatek 400v bulb, will see you right the way through.
This should give you a footprint of about 5ft square (when raised to full height) of high intensity light, the plants love it.... if you want to scale up, just do more of the same.
They are very reasonably priced, and give you good "Bang for Buck".
The extra penetration from the above type of light produces a very high quality and dense bud at all levels of the plant.
There are other ways, and I am sure others will advise on their choice, but for me, this would be my way - based on results I have achieved so far..... for example....
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