Help with new orchidarium

First thing for the seedlings - the genera you mentioned all need different light levels, so unless you can move the vandas and encyclias closer to the lamps, you shouldn't mix them with the lower-light plants. Yes, it is common that in-flask seedlings all need moderate light levels, once you start growing them individually, they should be transitioned to more standard light levels for the plants.

Yes, a heat mat will help them grow good root systems and take off.

33000 lm/m2 is a bit less than half of full sunlight. Again, not all plants will need that much light. Something else to consider is that the typical light level recommendations for a particular plant are the peak, noontime level, and the amount of light they get starts at zero at dawn, climbs to that peak at noon, then fades to zero again. If you are going to give them the same volume of photons with constantly bright, artificial lighting, you need to cut the intensity in half.

 

I my experience, the "recommended light level", as I said, was a noon peak for folks growing in natural light. If the plants are under 100% artificial light for about a normal day length, then a constant 1/2 of that is fine. For using artificial lighting as a supplement to natural light, you'll have to assess the amount of natural light the plant gets, and adjust the supplemental light accordingly.

For what it's worth, I had a "seedling incubator" in my basement, and the heating mats were on the same timer as the lights.

I can't help with those particular LED lights. Maybe Naoki will have time to check in on this. He's the real expert in that field.

 

Martel, I'm not familiar with that particular LED light. Looking at the spec., it will grow plants, but it is not efficient (3600 lumen from 50W = 72 lumen/W, much less efficient than most linear fluorescent bulbs like T8 or T5HO, and it is at the level of CFL). And with this kind of cheap flood light, the actual wattage may be different from what is stated (youtube link). So it may be better efficiency than what is listed. The price in UK may be different, but it seems to be over-priced, too. You can get this type of cheap flood light pretty cheap directly from China via eBay, AliExpress etc.

Common house-hold screw-in LED isn't so efficient in general, but something like this will give you better efficiency than the one you linked: Philips 12W PAR38.
This consumes 12W (I measured it to be 11.6W) and gives 1100 lumen (92lumen/W, which is slightly more efficient than T8 or T5HO). So 3 of those gives similar amount of light and uses 36W instead of 50W, and the initial cost is similar to the one you linked. This particular Philips bulb seems to have fairly narrow beam, so you might need to place it a bit further. But it might be good for the high-light orchids you listed.

I'm not sure about the size of the growing area. If you have a bigger area, linear light is probably better (more even coverage, and generally better efficiency). If you don't have budget up front, fluorescent is probably better. But if you shop carefully, you can find high efficiency T8 LED or shop light in hardware stores, which achieve around 100-110lumen/W.

Ray, I still don't know lots of stuff related to LED and photo-biology, so I wouldn't call me a "real expert"! I read about the science of light and biology a little bit in an attempt to minimize the wasted money and electricity for growing plants. I'm just a cheap-skate.

 

I'm with you on that, Naoki. To me, one huge gap in the available information is the spectrum. As we have agreed in the past, a pure red, and pure blue lamp may have the same PPF, but from a biological standpoint, will have entirely different effects on the plant. There are many "while" LED lamps out there that CAN be used for plants, but there seems to be no way to know which one is better.