I've been growing indoors under LED spots for a few years now. Two separate bookshelf gardens, one for cattleya-type light requirements and one for Paph-type light requirements. The catts also receive considerable natural light from a large north-west facing picture window.
I haven' participated in orchid forums for a few years now, but back when I was, I remember there seemed to be a strong preference for 5000k LEDs. I chose 3000K spots for the cattleya space because I figured that the supplemental natural light from the the large window would adequately balance out any blue spectrum deficiencies (if any). The quality of the light itself was pleasing and convincing to the eye.
Over time, I first noticed spectacular root growth. I also noticed that cattleya pseudobulbs tended to become more elongated and leaves shorter, although the overall texture of the plant was sturdy and correct. Blooming and the setting of new healthy growths (naturally the main objective) was far more than acceptable. And I have the lights on a timer so that, in summertime, when I have abundant sunshine through the window in the mid-to-late afternoon, the lights shut off. Most of my catts are yellowish green, which isn't particularly alarming. I remember old school veteran greenhouses whose long-grown cattleyas always looked simply dreadful but also sported magnificent blossoming. I try to strike a balance between good appearance and reliable blooming. Which means some constant fussing but what's a hobby for?
The paph garden receives next to no natural light. I also choose 3000K spots for these plants (fewer lumens, lower wattage, greater distance). Blooming is reliable and new lead production is actually quite amazing. Again, I feel I'm treading a fine line. There are a few signs of light stress which I'm constantly keeping an eye on. Also I've noticed a certain amount of "reaching" in the foliage (paralleling the elonging of my cattleya pseudobulbs), and this was commented upon at least once by others when I posted pics of certain plants in bloom.
I'm not actually unhappy, but find myself constantly referencing the preference for 5000K bulbs.
I recently read a post by Ray (of several years ago) which stated that he himself also was using 3000k bulbs for supplemental light.
Two reasons for this post: one being the possibility of experimenting with 5000k bulbs (which would result in quite a few unused bulbs with quite a bit of unused life hanging around) along with the expense of replacing 20 or so bulbs.
The other reason is just to say hello, and still kicking after a long absence. One can sort've go through stages orchid growing when interest flags, and then kicks up again, at least in my case.
Also am looking for options for feeding of orchids in sphagnum that doesn't result in it getting all green and gunky on top.
Thanks for reading.