Quote:
Originally Posted by Richard
Lumens is a measure of human perception of brightness. In professional horticulture, source intensity is always measured in Watts.
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Not exactly. Most typically, the power output (watts) of photoactive radiation (PAR) is used in professional horticulture. And, scientists often use photon flux (PPF). See
https://en.wikipedia.org/wiki/Photos...tive_radiation
I mentioned "lumens" only because the PAR value of most bulbs is not specified whereas the lumen rating is. All else equal, the bulb with the highest lumens is best. But, as I previously mentioned, at equal lumens, a household LED bulb has a higher PAR output than fluorescent. This is the typical spectrum of a household LED bulb:
This is the typical spectrum of a household fluorescent:
Compare with the action spectrum of an average plant:
And, you can see that the LED has much more PAR between 620 and 700 nm.