LED Lights

[e-spice]

Has anyone tried growing orchids under LEDs like this: Amazon Link If so, what is your experience with it?

I grow under several HPS lights and one is starting to buzz a little. I'm considering replacing it with an LED, even though I'm not crazy about the color of light.

Thanks in advance for any info!

 

[eteson]

I do have 6 very similar to the ones of your link. Phrags are growing very well.

 

[naoki]

LED technology changes so quick, it is difficult to keep up with. I don't have personal experience with this brand (most of them are rebadged from similar Chinese products) and this types of grow light doesn't give enough specification to judge the performance, but from what I hear, it is not an economical choice. It says 600W, but it is usually using 200-300W. If it is at 200W range, I'm pretty sure the following will outperform it with only 100W:
http://timbergrowlights.com/grow-light-kits/
100W model is $235, which gives a bit more than 4 bulb T5HO. My current light uses the same LEDs and driver (just 1/2 of the price) as the 200W model ($399), it covers 4'x4' area very evenly. It is a bit too much light for Paphs, so I have to dim it down to 160W. The kit is pre assembled, so all you have to do is to figure out how to hang them. These CXB3590 are usually at least 2x the efficiency (for photosynthesis), compared to that older style you linked. So you need only a half wattage to get similar amount of light.

If we assume that the chinese light is 300W and you go with the 200W CXB3590 and dim down to 150W, you'll save about $85 per year (365 days * 13 hours per day * 150W difference * $0.12 / 1000). I think $0.12/kWh is the average electricity cost in the US (but you might want to check it, I'm paying $0.20/kWh). So it becomes cheaper around 3 years. I'm pretty sure that high quality CXB3590 will last at least 3 years or more easily, but I'm not so confident about Chinese models from my experience. I had some cheaper Chinese ones, which lasted well (still works, but don't use it regularly any more due to inefficiency), but I had to keep fixing others (replace dead diodes).

Cree CXB3590 used to be the king of PAR efficiency, but there are others which are better (and much cheaper) now. But these are mostly for DIY people so far.

 

[gego]

If you want to try before going DIY, go to homedepot and get those new Cree LED bulbs that state something like true color (I forgot). Select 3000K, I just find this color to be more effective. I forgot the wattage (~16W) but it is equivalent to 75W incandescent lamp. It cost around $17. Buy a few like four and space them equally over the plants you want to test. With paph and phals, I set the height of the bulb to read from 600-900 FC depending on the type of plant. Gradually increase light if you think it needs more. Just be cautious, it may seem low light but consider that the light is constantly directed to the leaves for so many hours. You will have to buy sockets for the bulbs and wiring or just buy a set with a reflector. Also available at home depot.

 

[eggshells]

Has anyone tried growing orchids under LEDs like this: Amazon Link If so, what is your experience with it?

I grow under several HPS lights and one is starting to buzz a little. I'm considering replacing it with an LED, even though I'm not crazy about the color of light.

Thanks in advance for any info!

I bought a similar one from amazon. I'm very pleased with it.

 

[Happypaphy7]

I've had something similar a long time ago. Plants grew very well and flowered under it.
I just hate the colors. Rather freaky to me.

 

[gonewild]

I've been reading a lot of research papers and grower reports on LED light color. It seems that cool white light produces very good plant growth compared to other colors. Especially true on slower growing plants like orchids. I doubt there is any reason to use colored lights in a hobby growing environment unless you like to avoid seeing natural colored leaves.

Using colored light to supplement sunlight is a lot different than having the color being the only light source.

 

[JAB]

PM is incredibly difficult to spot under those pink/red LED's as well

 

[naoki]

gego, the fixture with cxb3590, which I linked is not DIY. It is pre-assembled.

I agree with you, Lacnce, at this moment, there isn't many reasons to go blurple at this moment (other than they are cheap initially). Nothing is wrong with them, neither, and plants do grow ok, as long as they get enough light. This situation can change once LED companies put more efforts for horticultural LEDs.

Can you share the literature about the LED effectiveness in slower growing plants?

Within white LEDs, there seems to be slightly higher PPF per watt in warmer white than cooler white in some brands (e.g. citizen), but not always. But the difference is pretty negligible. So in terms of photosynthesis, I personally don't care too much about CCT (within 3000-5000K). Also you can see "Effects of Light Quality" section in this paper: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099010 Here is the relevant quote:

Over the past 30 years, numerous longer-term studies with whole plants in higher light indicate that light quality has a much smaller effect on plant growth rate than light quantity [6], [7]. Light quality, especially the fraction of blue light, has been shown to alter cell expansion rate, leaf expansion rate[8], plant height and plant shape in several species [9]–[11], but it has only a small direct effect on photosynthesis. The effects of light quality on fresh or dry mass in whole plants typically occur under low or no sunlight conditions, and are caused by changes in leaf expansion and radiation capture during early growth [6].

The last sentence here is similar to what you stated, but the study didn't use low light plants. It was done in low light with high light plants. So I'm curious about the source of your info.

I can see the advantage of 3000K when plants are sensitive to red:far red ratio (e.g. photoperiodic plants like some Cattleya and some medical plants).

 

[gego]

Yes Naoki, my observation is that the 3000k LEDS produced nice shiny color green on my paph and phals. I have this test for over a year now and the difference is obvious.
3k K is almost the same light in the morning and afternoon.

Sent from my HTC One using Tapatalk

 

[gonewild]

Can you share the literature about the LED effectiveness in slower growing plants?

I dont think I saved the pages, but I'll have a look. There was no definitive data that proved anything but overall the majority of observations was that there was little or no difference (yet). Except for fast growing leafy plants like lettuce and the colored light yielded more weight/volume faster. But one paper that grew the plants on to maturity found the plants growing under 100% colored light yielded less mature volume and fewer flowers than those under white light.

I have no personal experience yet with using colored light so my comments are based on what I'm learning from reading to formulate my own opinion. But I am trying really hard to find something that makes me believe colored light is worth the annoyance of looking at it.

 

[gonewild]

Here is one paper:

http://file.scirp.org/pdf/AJPS_2016032915221970.pdf

It definitely shows color can enhance flowering. But they only consider using color as a 10% supplement to white light. I get from reading this that using the color for all stages of growth would likely decrease overall long term health/growth because the light color directly affected the plants natural hormone production. Specifically the gibberillin levels were elevated which over a period of time would cause plant growth to stretch and stretched growth on orchid plants growing under artificial light is not a good condition to have.

 

[naoki]

Thank you for digging up this recent paper, which I wasn't aware of, Lance! It basically says that the light spectrum doesn't matter too much for photosynthesis. But as we have been saying, it can influence the other physiological aspects like photomorphogenesis, flower induction, etc. It is interesting that they saw a dramatic increase in flower initiation when there are lots of red compared to far red light. I have thought that light period isn't important for tropical Phalaenopsis. But the results suggest that long day (short night) can possibly induce flowering, too (my interpretation). This is rather counterintuitive because P. aphrodite flowers in late winter, early spring.

With regard to gibberellin, it is just a signal induced by some other environmental cue (here R:FR ratio). So we don't know if they will continue GA production for a long time. It would be interesting to do the similar experiment with Paphs. As we discussed before, there is a small evidence showing GA can induce flowering in some Paph species. But we don't know high R/FR will induce GA production in Paphs.

Once we know more about the effect of light spectrum on orchids, monochromes will become more valuable (for manipulation). Spectrum manipulation could be potentially used by people who are interested in award. But the problem is this kind of response is rather species specific. Also the optimum light spectrum will be different for different developmental stages.