Working out minimum and maximum LED lighting requirements per square foot ??

[hydromania]

So with HPS & MH the rule of the thumb is 50w per square foot ..
With LED because of the lower wattage usage do you work out the minimum requirements with PAR output per square foot or Wattage from the wall per square foot??

 

[wizgrow]

35-50 is what I have seen stated

 

[Techhead]

Still watts per foot, and that is true watt from the wall more or less. I've heard 30 min, and 50 max, but is there a max? 50 per foot of HPS, and or MH I think is min.

 

[madscientist9]

You might want to do some further research into this as my 400 hps I could keep with in about 6" of the plant and my 600 was about 10" and neither one was able to penetrate that well with about two feet from the bulb being the max for good growth. My LED's are all more then 18" and closer to 24" from the canopy and different strains all show great side branching and no stretching for light.