So, back to the point I was getting at, is that a balanced spectrum with relatively equal blue and red spikes is where the current high performance LEDs are at (and, yes, far red supplementation).
Like aqua said, blue will make them short but so too will red, come flowering... when we want to minimize stretch and also get that nicely packed bud structure.
The big issue with LEDs (except COBs) is intensity and penetration, so, generally, the shorter the plant, the better.
imo penetration comes from mostly red and believe it or not green. LED penetration is actually quite good. We need to look at it as not the photosynthesis of the the top leaves exposed directly to light but the whole plant and blurple lacks green for penetration. I think this is where we got into the LED doesn't provide good penetration idea and test results. Green albeit more inefficient than red and blue still can account for a good amount of photosynthesis because of its ability to penetrate through leaves and into the lower canopy. Once thought that plants reflect all green light and don't use it as seen by many that use it in the dark to see them. I had that convo with
@MIMedGrower oh probably more than a year ago and I figured at that time that the intensity is the key to whether it could affect flowering as some reported it did. Everything I have found since then supports that and green as long as its below a certain ratio is important.
Bottom line is a full spectrum light is beneficial and the ratios of spectrums are important. The spectrum benefits change based on the type of growth we want. Yes I realize the sun does go from 3kto4k and we don't have to either... but does that mean there is no benefit to doing so? Absolutely not.
I sacrifice optimal vegetative growth for a spectrum that leans more toward root and shoot development. Yes my photosynthetic rates could be better under a different spectrum but I'm thinking buds.
If you ask me all the newer LED are going more blue for the pretty plants, robust vegetative growth with more leaf surface area, reducing stretch and tight dense buds. Also I feel a slight reduction in yield and this is being combated with the addition of IR.
JUST MY OPINION.... take it for what it is... some guy on the interwebs thoughts