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.
Threaded Mode
