Hey what’s up Scotty, The Dude and Guru… I’m a huge fan of the show I listen to you guys everyday at work. I always get lots of laughs and retain a lot of knowledge from your podcast. What’s a good rule of thumb for watts per square foot for an LED grow? I’m currently in at 3 x 3 tent for my flower and I have roughly 62 watts per square foot, is that too low? Thanks again for the help, peace.
62w per square foot in a 3×3 would be 558w of LED in a 3×3…. which sounds like too much.
An HLG 600 is supposed to cover somewhere between a 4×4 and a 5×5. This works out to somewhere between 24-36w per square foot
Efficiency of leds can vary a lot too. You get way more light per watt when you use more efficient diodes. So the brand and quality of led you are using makes a big difference.
I’m not sure wattage per square foot is really a good way to measure light anyway. I think it’s more important to look at the actual foot print of the light you are using.
I know the old rule of thumb was 50w per square foot, this was with HID systems. LED are more efficient, offering the same output using half the wattage compared to HID. So does this mean 25w per square foot is enough? Most likely not, I prefer to stick with the old rule of thumb of 50w per square foot.
The geek answer to this would be to find your current DLI for the “lights on” period. Does that meet or exceed the levels established for Cannabis? Do you have a lux meter or Par meter? Those will help find the technical answer if you are seeking it.
Also, keep in mind, regardless of the wattage, the corners will always suffer from lower PAR compared to directly under the light. Which is what Soup was kind of saying above. Total watts per square foot gives you an idea of coverage, but not a footprint of that coverage distributed evenly.