I'm trying to decide between a couple of CFL bulbs for supplemental lighting. One option is 5600k and 91 CRI, the other is 6500k and 80 CRI.
Am I right in guessing that the color temp matters more to plants?
CRI and Color temp are basically the same thing. They are both measures in how we "see" an illuminated object. How that affects plants is subject to debate.
Latest research has shown that PAR (photosynthetically available radiation) is more important since lux, lumens, CRI and color temp are how our eyes 'see' things.
It is well worth doing some research on.
Have a great day,
Thanks SCG. I was just reading on a thread here long ago that CRI doesn't matter to plants. I beleive I know what you are saying, but one problem is that sometimes it's hard to even get basic data about a bulb from online listings. PAR for example, I've not seen this listed for any CFL I've looked at. This means I'm just sort of winging it I guess. But at least now I'm not going to agonize over color temp.
In my opinion (reiterate "my" ~ and nothing more than an opinion), I think you would be fine using either one of the bulbs you mentioned above, and with a higher CRI (80-100) light source 'things' can look better.
Included a link worthy of review:
Although the above link is geared more at giving an overview of acceptable color rendering index for professional imaging, it has usable information that can be applied to growing under lights.