T8 lighting...
 

I'm in the process of bringing in my 'chids for the winter. I have them on shelves and was wondering that if I put up some T8 lights with like a few 6500K bulbs if that would be efficient to grow them over the winter. Can someone please shed some light on this for me?? Pun intended of course!!! :rofl:

T8s will work fine if you have enough of them and can get them fairly close to the plants. If you have a good light meter, you'll need at least 2500 foot-candles for about 12-14 hours. What kind of orchids?

T5's are more efficient, aren't they?

And 2500 fcs is a hell of a lot of T8s. If you need that much light, better off going with T5s.

But it completely depends on what kind of orchids. If you grow Dens or Cats or something with tall leaves that need a bit of distance between the shelves, go with T5s.

If you grow low light plants or small seedlings, go with T8s. But even then, if you find yourself needing 3 or 4 in a bank to get sufficient light, probably better going with T5s.

I use mainly single T8s in my shelves (because i have them mainly for deflasked Phal. seedlings that are very light sensitive). In that case just a single T8 can redden young leaves.

But with a reflective surface above the light i've found a single or double T8 sufficient for Phal. growth up to maturity. That's about 500fcs for 10 - 12 hours a day. I get severe reddening with anything more than 1000 fcs for that period of time in my mature Phals.

Ray T5s are more efficient for the amount of light they put out, but in my situation i don't need and don't want that much light. If you want a good amount of space between leaves and light, or if you keep moderate to high light orchids, you do need the T5s.

How can I figure out how many foot candles I have??? I have 4 T8 6500K lights that produce 2800 lumens. The only reason I used T8's is because we don't have anywhere to purchase T5's and honestly I didn't have the time to order them. Maybe later down the road.

in my experience, I just got a T5 14 w 24" undercabinet light at HD for $18. Wanted to supplement my S. window where I have been using a 23 W CFL [100W equiv]. The light of the small T5 seems higher than the CFL. Not so much noticeable by the naked eye but when I took a photo of a pot of young keikis last night I saw that the side of the T5 was way more overexposed [left side].
I got the undercabinet because it is lightweight and I could tape it to a shelf next to the window.

at HD you can get a 3 ft T5 setup for 25 dollars [+ 6$ wire]. I think it seems more efficient than T12 [I have 2 setups with 2 bulbs each]. and a tube is 15/ 20 W vs 40 so in the long run if I switch to T5 I may save on the electricity bill.
seems a 15/20W T5 bulb is quite brighter than a 40W T12.
Anyway some new leaves / keiki of a phal under the 2 T12 are purple so it may be enough. but I also have Vanda, Dens, Catt. etc.

I dont know if T8 are efficiency wise closer to T12 or T5.