Originally Posted by Organics
Thanks for the info on the background, also from my understanding the red/blue won’t make color pop on plants, they will how ever change the type of growth you receive. Red for example will encourage more leggy growth this response is due to areas that receive higher amounts of “red” light tend to be areas shaded by other plants where its advantageous to grow fast and tall. Color tends to be a response to light intensity.
Originally Posted by DPfarr
Depends on the wavelength of the red in respect to becoming leggy.
The shorter wavelength can travel through foliage or destruction by refraction. Conversion to the active form of phytochrome making it grow leggy.
My understanding is you both have a piece of it but the whole story is more complicated. Red light does make plants grow lanky but only if you use pretty much only red light. To be clear we are not talking about the far red part of the spectrum. If blue light is added you get normal plant growth. This is why so many people are selling these incredibly ugly grow bulbs that are a mix of red and blue leds to create this truly heinous purple light. Normal amounts of red light help plants flower, or in situations where they don't flower and are getting enough light otherwise to grow properly, and then if they can, red light helps plants turn red.
On the aquarium side this is a pretty common concern since some of the aquatic plants will turn various shades of red when exposed to enough co2 and light. But light with too much blue in it won't do the trick. Thus the best aquarium leds often have a much warmer spectrum, something in the 5000s to low 6000s.
Anyway in my case I am adding the reds and the greens for people not for the plants. The cool whites will grow the plants great, but if you shine green light on a plant it will mostly bounce off and thus make the plant look 'more' green. Same for red which is why I mention colors popping.
Here is some random quick write up I found on red light plant growth: