Lettuce bolts like mad in the summer. I've seen NFT setups using proper nutrition and mass CO2 under sunlight produce lettuces the size of my torso, but that was a highly tuned
nutrient solution and 1200+ppm CO2 at all times.
I had my guys give me a measurement of my current 1w
led bars used for growing lettuce. 138 umol m^2 s-1 from 300mm away. If you could get a quantum flux reading of whatever
lights you ultimately use indoors, I'd like to know, especially if
fluorescent, as my bars are of equal wattage to a typical T8 at 32w.