Artificial Lighting

[gdupont]

Hey everyone! So, today I purchased a small glass 5.5 tank 16 3/16" x 8 3/8" x 10 1/2" today, with a lid and a humidity and temperature monitor. I plan to also add a cpu fan as soon as I can get my hands on one. I have a Laelia alaroii, a couple of Dendrophylax, an Ascocentrum pumilum, and a couple of others that like warmer and brighter conditions. The only window is a small west-facing window, so I'm considering moving them out of that light and trying artificial light. I don't have a heater in the tank, so I was thinking trying non-LEDs to raise the heat a bit as I think the room will probably be a little chilly, or perhaps LEDS and a water heater in a water bowl. At my local pet store they sell a lid for this tank which has a 14 watt T8 "Full Spectrum" bulb, would this fry my orchids or would it be good? I'm totally new to this, so please excuse my lack of knowledge. Thank you!

[tropterrarium]

The idea of adding fluorescent to raise temp works. I would rather go for T5 bulbs rather than T8. The former have higher light output.
Re using heater in water bowl, it will also raise humidity quite a bit. I turned mine off again because of excessive humidity and condensation on the plants, which then will lead to leaf rot.
There are some low temp water heaters, that can be placed in air, possibly with CPU fan blowing over it. Heat rocks from reptile stores break rather quickly in humid environments. done that a bunch of times.
There are also undertank heat-mats. Make sure to get the lower temperature version (often referred to as rainforest type) rather than the high temp type (referred to as desert type).

Notice, there is a dedicated terrarium section on Orchidboard.

[dnatural1]

Hi GDUPONT,

First of all I'm glad to have someone to share this type of experience with - don't see much on horticultural lighting in this forum.

Now to start answering you query. Horticultural lighting works - some work better than others. I am currently using LEDs - previously I used aquarium type fluorescent lighting. I found LEDs far better than fluoro lighting. They are much more frequency specific (I'll explain this later) and much more effcient in terms of light emitted per watt of power. I have not tried high intensity discharge (HID) type lighting (eg Sodium lighting) so cannot comment. From what many say HID lighting works very well. The main issue you'd have in a small terrarium is is heat - HID devices are generally high power and they can easily fry plants in a small enclosure like the one you're describing. The following describes my experiences with LEDs - I won't be considering anything else given the results I've got.

Now to some basics. Plants absorb only specific frequencies (colours) of light. Basically (and a bit simplistically) they need colours in the BLUE spectrum and colours in the RED spectrum as follows:

RED: 630 to 670 nm; RED stimulates flowering
BLUE: 420 to 470 nm; BlUE stimulates growth

Perhaps surprisingly they do not need GREEN light. That is why most leaves look green - basically it's the colour discarded by the plant (RED and BLUE are absorbed) and hence what we see.

For a fuller article on this see: https://en.wikipedia.org/wiki/Chlorophyll

So you'll need RED LEDs and BLUE LEDs. Now this is where it gets a bit tricky because not all LEDs are the same. A LED's light quality depends on the quality of the process that manufactured the semiconductor (called the die) from which the LED is made. It also depends on the lens placed on top of the die. The lens is used to direct the light. With 5050 LEDs (like the ones I've got) this is 120 degrees. I bought my LED strips from China and I believe that I got a good deal. But I read stories on the net that you do not necessarily get what you expect unless you go to name brands (Eg Philips, Osram, Cree, Epileds, ...) which also attract a premium price. The vendor I got mine from is: led-top365 items - Get great deals on LED Panel Light, LED Ceiling Lights items on eBay Stores!. The reason I chose them (from many similar ones) is because they answered all my question. Just search EBay using "horticultural grow lighting LED" and see how many horticultural LED sources you get.

The strip lights I got are similar to these:
5pcs 0 5M 25W 5050SMD LED Plant Grow Strip Light Bars Garden Supply DC12V Power | eBay
They are 50 cm long and contain 36 LEDs. There are many form factors to chose from ie not just strip form.

You can chose whether to get all RED, all BLUE or a combination of RED and BLUE. I Chose 3 types of 36 LED strips; 24xRED+9xBLUE LED combination, 36 LED BLUE strips and 36 LED RED strips. This gave me choice to vary the RED:BLUE ratio as I need. Currently I am using a converted 4 foot by 1.5 foot aquarium as my terrarium. I am using four RED:BLUE LED strips (to promote flowering and some growth) and two BLUE LED strips (to promote growth). All in all I have around 50W to 55W going in. I could do with a bit more. The results have been very good. I flowered plants which I only managed to do, very poorly, once before. One of them (Dendrobium ruginosum) has 3 spikes with 8 flowers in total - I only managed to get 1 spike with maybe 2 flowers on it before.

There are downsides to my setup. One is that the humidity inside get very high (over 90% most of the time) - my terrarium is enclosed to retain temperature during Winter. Some plants love this - others hate it. So choice of plants is important. Another thing to watch out for is fresh air. I do have small apertures at the top and also a fan for air circulation but I found the need to open the covers for around an hour each day to ensure a good supply of fresh air. Finally but not leastly you need to keep the base of your plant off the bottom of the terrarium so that they are not permanently in contact with any accumulated water on the bottom of the terrarium. The last point also indicates the need to siphon water off the bottom on a regular basis (ie every time you water).

Could say lots more as I've been experimenting with this kind of thing for about 5 years but this is long enough for now. I'll post some picture and a few more points hopefully tomorrow.

Joe P.

[Ray]

Joe, a lot of that is good info, but the part where "plants don't use green light" is simply incorrect. Plants actually use the entire visible spectrum, and a bit beyond in both directions. Yes, chlorophyll primarily absorbs in the red and blue portions, but it DOES absorb other wavelengths, as well, plus there are other chemicals that absorb other wavelengths too.

[Subrosa]

Also while plants can be grown under just blue light they won't flower. Most plants will etiolate badly and die before they get to flower under just red light. A mix of the two is required to get reasonably normal growth. An addition of other wavelengths is required to get a normal appearance to the human eye.

[gdupont]

Originally Posted by dnatural1

Hi GDUPONT,

First of all I'm glad to have someone to share this type of experience with - don't see much on horticultural lighting in this forum.

Now to start answering you query. Horticultural lighting works - some work better than others. I am currently using LEDs - previously I used aquarium type fluorescent lighting. I found LEDs far better than fluoro lighting. They are much more frequency specific (I'll explain this later) and much more effcient in terms of light emitted per watt of power. I have not tried high intensity discharge (HID) type lighting (eg Sodium lighting) so cannot comment. From what many say HID lighting works very well. The main issue you'd have in a small terrarium is is heat - HID devices are generally high power and they can easily fry plants in a small enclosure like the one you're describing. The following describes my experiences with LEDs - I won't be considering anything else given the results I've got.

Now to some basics. Plants absorb only specific frequencies (colours) of light. Basically (and a bit simplistically) they need colours in the BLUE spectrum and colours in the RED spectrum as follows:

RED: 630 to 670 nm; RED stimulates flowering
BLUE: 420 to 470 nm; BlUE stimulates growth

Perhaps surprisingly they do not need GREEN light. That is why most leaves look green - basically it's the colour discarded by the plant (RED and BLUE are absorbed) and hence what we see.

For a fuller article on this see: https://en.wikipedia.org/wiki/Chlorophyll

So you'll need RED LEDs and BLUE LEDs. Now this is where it gets a bit tricky because not all LEDs are the same. A LED's light quality depends on the quality of the process that manufactured the semiconductor (called the die) from which the LED is made. It also depends on the lens placed on top of the die. The lens is used to direct the light. With 5050 LEDs (like the ones I've got) this is 120 degrees. I bought my LED strips from China and I believe that I got a good deal. But I read stories on the net that you do not necessarily get what you expect unless you go to name brands (Eg Philips, Osram, Cree, Epileds, ...) which also attract a premium price. The vendor I got mine from is: led-top365 items - Get great deals on LED Panel Light, LED Ceiling Lights items on eBay Stores!. The reason I chose them (from many similar ones) is because they answered all my question. Just search EBay using "horticultural grow lighting LED" and see how many horticultural LED sources you get.

The strip lights I got are similar to these:
5pcs 0 5M 25W 5050SMD LED Plant Grow Strip Light Bars Garden Supply DC12V Power | eBay
They are 50 cm long and contain 36 LEDs. There are many form factors to chose from ie not just strip form.

You can chose whether to get all RED, all BLUE or a combination of RED and BLUE. I Chose 3 types of 36 LED strips; 24xRED+9xBLUE LED combination, 36 LED BLUE strips and 36 LED RED strips. This gave me choice to vary the RED:BLUE ratio as I need. Currently I am using a converted 4 foot by 1.5 foot aquarium as my terrarium. I am using four RED:BLUE LED strips (to promote flowering and some growth) and two BLUE LED strips (to promote growth). All in all I have around 50W to 55W going in. I could do with a bit more. The results have been very good. I flowered plants which I only managed to do, very poorly, once before. One of them (Dendrobium ruginosum) has 3 spikes with 8 flowers in total - I only managed to get 1 spike with maybe 2 flowers on it before.

There are downsides to my setup. One is that the humidity inside get very high (over 90% most of the time) - my terrarium is enclosed to retain temperature during Winter. Some plants love this - others hate it. So choice of plants is important. Another thing to watch out for is fresh air. I do have small apertures at the top and also a fan for air circulation but I found the need to open the covers for around an hour each day to ensure a good supply of fresh air. Finally but not leastly you need to keep the base of your plant off the bottom of the terrarium so that they are not permanently in contact with any accumulated water on the bottom of the terrarium. The last point also indicates the need to siphon water off the bottom on a regular basis (ie every time you water).

Could say lots more as I've been experimenting with this kind of thing for about 5 years but this is long enough for now. I'll post some picture and a few more points hopefully tomorrow.

Joe P.

Wow, what a thorough response! Thank you so much. So after taking your advice I looked on that vendor's ebay store and found the following product:

25W 0 5M LED Grow Light Strip Garden Plant Hydroponic Indoor Red Blue DC12V | eBay

Do you think these would be a good choice? My tank is just over 16" (41 cm) across on top.

Another option I found are the following 2 LED bulbs on amazon:

LED Grow Light Bulb for Indoor Plants

Twin Pack LED Grow Lights for Indoor Plants: 12 Or 18 Watt

[dnatural1]

Hi gdupont,

I wouldn't go with the first choice (25W 0.5M LED Grow Light Strip ...) as:
1 - It's longer than your tank (50cm strip on a 41cm tank) and hence you'll be wasting the light that falls outside the tank
2 - Each strip is 5W. You'll be needing to use at least 3 strips (15W). You have to find a way of fitting them over your tank. As the strips do not come with a housing you'll have to work out how you're going to do this.
3 - You need to organise a 12V DC 30W power supply (as I had to when I bought strips).

Your other choices are more promising as the form factor (round) is more suitable for your case AND you just plug them into the mains using a screw (Edison) connector and you're in business.

I'd go with your second choice "Twin Pack LED Grow Lights for Indoor Plants" as it's spectrum coincides well with the absorption spectra of chlorophyll a "The absorption peaks of chlorophyll a are at 665 nm and 465 nm" (see https://en.wikipedia.org/wiki/Chlorophyll). Must admit that I'm not an organic chemist so I'm going by what Wikipedia says. The product description also says "Recommendation is to use 1 bulb per 30 sq in area at 30 in stand-off". I'd start using 1 and carefully introduce another (using it it for, say, 30 minutes at a time and checking for leaf burn\bronzing).

Your tank is quite small and you may have difficulties fitting many plants in it. You may soon find that you need a bigger tank.

[zelda]

I really hate the magenta glow of LEDs, but love white LEDs. I ordered two huge LED bulbs from Ray that give off warm white light, and so far I love them. They are bright and don't make my plants look like they're growing in a pot farm.

He also has bulbs for vivariums.
https://www.firstrays.com/cart/Light...rium-Grow-Lamp

Can you use a heated seedling mat to put underneath your tank?

[naoki]

Originally Posted by dnatural1

Hi gdupont,
I'd go with your second choice "Twin Pack LED Grow Lights for Indoor Plants" as it's spectrum coincides well with the absorption spectra of chlorophyll a "The absorption peaks of chlorophyll a are at 665 nm and 465 nm" (see https://en.wikipedia.org/wiki/Chlorophyll).

dnaural1, as Ray has pointed out, you are making a common misunderstanding here (I used to make this wide-spread mistake, too). Chlorophyll absorption is just a part of photosynthetic efficiency.

See the red line in the figure next to yield photon flux section:
https://en.wikipedia.org/wiki/Photos...tive_radiation
This graph shows how different wavelength may influence the photosynthetic efficiency. You can compare it with the chlorophyll absorption spectrum, and you'll notice the difference. One thing I should note is that this photosynthetic action spectrum is measured from full sun crop plants. Orchids might have quite different responses.

At this moment, many of the LED grow light makers are moving toward white + monochromatic (a bit of red) from the old fashioned red/blue + a couple monochromatics. This is mainly due to the rapid improvement in performance/cost of white (compared to mono's). So you'll get higher PAR efficiency for a given emitter cost with high-performance whites.

[dnatural1]

Hi zelda,
Apologies for not answering earlier. I am currently rather busy.

I have used a 100W heating mat WITH THERMOSTATIC CONTROL. I placed the heating mat right under the terrarium (ie right against the glass). On the other side of the heating mat I placed polystyrene foam for insulation so that the mat's heat flows into the terrarium rather than below into the base.

The system worked fine from a temperature control point of view. However, when I was maintaining the system after Winter, I noticed the polystyrene foam had melted and stuck to the bottom of the heating mat. I suppose it doesn't take much to melt polystyrene foam.

I used the heating mat during another Winter this time replacing the polystyrene with a camping foam mat and this worked better although even with this I noticed signs of heat stress in the foam.

I needed to use 100W to maintain temperature (25C) during our Winters so could'nt use a lower wattage heat mat. I now have replaced the mat with a small 100W electrical heater (with a fan) attached to the ceiling of the terrarium. This also works from a temperature management point of view but also has some minor issues (the hot air seems to be drying some of the plants in its path)

---------- Post added at 10:51 AM ---------- Previous post was at 10:27 AM ----------

Originally Posted by naoki

dnaural1, as Ray has pointed out, you are making a common misunderstanding here (I used to make this wide-spread mistake, too). Chlorophyll absorption is just a part of photosynthetic efficiency.

See the red line in the figure next to yield photon flux section:
https://en.wikipedia.org/wiki/Photos...tive_radiation
This graph shows how different wavelength may influence the photosynthetic efficiency. You can compare it with the chlorophyll absorption spectrum, and you'll notice the difference. One thing I should note is that this photosynthetic action spectrum is measured from full sun crop plants. Orchids might have quite different responses.

At this moment, many of the LED grow light makers are moving toward white + monochromatic (a bit of red) from the old fashioned red/blue + a couple monochromatics. This is mainly due to the rapid improvement in performance/cost of white (compared to mono's). So you'll get higher PAR efficiency for a given emitter cost with high-performance whites.

Hi naoki,

I did have a look at the link you pointed out. I was aware that there are other compounds involved in photosynthesis besides chlorophyll A and chlorophyll B - such as the carotenoids. These also have absorption peaks "close" to those of the chlorophylls.

There also seems to be some uncertainty about what exactly is going on. The article you referenced states "The YPF curve was developed from short-term measurements made on single leaves in low light. Some longer-term studies with whole plants in higher light indicate that light quality may have a smaller effect on plant growth rate than light quantity." Not too conclusive.

At the end of the day I decided to follow what others have reported as successful based on actual experience. Having done so I can state that by using RED-BLUE lighting, at around 60W, over a 4 foot terrarium I have achieved significant growth and flowering. I would love to hear how I can improve on that ideally based on actual experience. Also some clarification on what you mean by "white" light sources - I am under the impression that white LEDs are quite common (in fact more so than mono-chromatics).