# 4000K Lighting Bulb



## stevenlau (Jul 21, 2009)

Can a 4000K lighting bulb be utilized by plants? If it helps, the brand is Osram T5NO and has a CRI of 80. I already have 2 865 (6500K) bulbs installed and wish to add an extra one of 840 (4000K) if it helps better plant growth. The bulb itself looks yellowish and here is the link of the spectral power distribution :

http://www.osram.se/osram_se/Ljuskunskap/Spektralfoerdelningar/Lysroer.pdf

Thank you for any input.


----------



## gpodio (Feb 4, 2004)

The 9xx series would be a better choice due to the use of more phosphors, but there's absolutely nothing wrong with 4000K bulbs, red plants tipically look redder under lower kelvin bulbs such as these. 

Obviously spectrum and CRI can vary between bulbs of the same kelvin rating so we can't generalize too much on the kelvin rating alone.

Giancarlo Podio


----------



## ryan10517 (Apr 28, 2010)

there is a lot or red light in that bulb (peaks around 610 nm) so would need a more bluish light probably around a 10000k to help as well. But the 4000k would definitely help plant growth.


----------



## stevenlau (Jul 21, 2009)

Thank you very much for the info, of course I would like to look for 9XX series bulbs but my lighting fixture is really give me not much choices of T5NO bulbs that available here to be bought and I can only found the Osram brand. 

I will try to get another brand 'Dymax' that stated 10000K or 12000K but I'm not sure it's accurate or not, to be mixed with 6500K and that 4000K hoping to have better result.

Yes, that 4000K is really yellow and I seem to not like it very much mixed with 2 6500K bulbs, I will try to replace one of those 6500K with another 10000K or 12000K to see if it will bring more white to the effect.


----------

