K, I have been growing for `bout 7 years (on this stretch, I grew few years ago but not counting that) I just finished a series of light trials. I used to use sunlight, in a BIG shed with a perspex roof. All natural it grew adequate plants for my own needs but nothing great.
Then I moved into a place where I couldn`t really use the shed `cos theres not enough light to the garden. (too many surrounding trees).
So I grow in two double cupboards. First I tried Flourescents and I was happy for a while, again adequate plants for my needs but not great.
Then I made the foray into testing the new LED lighting. What a bloody dissapointment!! to say the least.
Not enough heat to keep them warm, and the main problem with led`s is that you can`t concentrate the light in one area. The bigger the spread of your array of lights the bigger the spread of the actual light coverage. That was crap, don`t do it.
Then I took the advice of others and went for the 400 watt hps.
Damn! It was too hot even with the fan going all the time the lights were on, two feet above the plants it still burnt the leaves.
Bottom line..... for a two by three foot cupboard I have a 250 watt HPS I use the fan set on timer to keep the heat at optimum. And my plants are the best ever!!!
I love them again.
I still use floro`s for seedlings and cuttings in the second cupboard and thats fine, but the best lighting now is my 250 watt hps. Will never change it now.