Just thought I'd try to summarize a lot of comments that have been made here over the life of this section of the board. Maybe this can be made a sticky?
Light Intensity
We continually read figures about the needs of orchids as per light. Something like "This orchid needs 1200-3000 foot-candles light" or whatever. My findings are that those figures are not valid when growing under lights. I am convinced that those figures are based on greenhouse growing or outdoors growing where the sun rises in the AM at a very dim light level, then increases to a high slightly after lunch time then starts to dim until sunset. The color (Kelvin) changes all the while. Under lights, we grow at a constant Kelvin, at a constant light intensity (foot-candles) and a constant timing over the year. This can lead easily to purple coloration in orchids at 1200-1500 FCs where the subject is supposed to take full sun!
Plants require only certain parts of the light spectrum to grow and bloom.
While this may be true, there is a matter of practicality for most of us. While "cool white", "warm white", etc. bulbs all have their own spectrum, "full spectrum" bulbs promise to deliver the whole range of light as perceived by normal human beings. This also works for most plants. Yes, there is a mid range not totally used for plant processes, but we, as human beings, use that range in viewing the plants. Therefore, we need that middle spectrum to fully appreciate the flower colors.
What are the best type artificial lights for orchids (or any other plants)?
This is a very heated discussion. There are florescent tubes (both straight and twisty), there are high intensity discharge bulbs (so-called hot lamps), there are incandescent bulbs and spot lights, there are LED lights. There really are a lot of different solutions. Which is right for you? Well consider the following:
For florescent fixtures: they run cooler than most (except LED), they can output very high amounts of light per unit energy consumed (depends on type of bulb/fixture), with the coily bulbs they can be compact and easy to install or position, for the bi-axial CF fixtures, they give off lots of light at relatively cool temps.
There are basically 3 types of florescents you'll run into (plus a couple special types - based on 48" tubes). There's T12 (like shop lights) - these are typically 32 watt, fairly dim and starting to disappear. There's T8 (like kitchen florescents) - these are typically 40 watt, much brighter than t12, commonly available in big box stores, and very effective for growing orchids. There's T5 (special thin bulbs only available through specialty growing shops like Hydroponics Stores.) These are the highest lumens per watt consumed for the florescent tubes. Their use is dependent on a high quality fixture to reflect maximum lumens back to the plant.
Compact Florescent: These are basically a compromise, but a valuable one at that. A lot of the potential light energy is lost back into the system, by design. However, what is projected is very bright and the fixture is more easily positioned than with many other fixtures. It still has the coolness of the straight tube fixtures, but with slightly less effeciency of light output. It serves a very useful need for many people.
For the High Intensity lamps (HID and HPS): they give off probably the highest amount of light possible for the amount of energy consumed, They can be positioned further from the plants than with other light sources, they last longer while burning, They are available in two different light colors (Kelvin) and hold the color temperature and output probably longer than any other style bulb.
Incandescent bulbs, including small "plant light" flood light bulbs:
These bulbs tend to be popular where space is an issue, where very few plants are involved, where heat is not an issue (these give off lots of heat) and where expense is an issue. They can be effective only under these conditions. There are lots of drawbacks for these bulbs.
LED Bulbs, particularly the red/blue spectrum:
I won't say much here, other than these are still in the design stage, for the most part. Yes, there are a few products that seem to promise enough light to grow orchids, but the cost is still high for the output compared to the solutions above. For now, see the threads:
http://www.orchidboard.com/community...hts-equal.html
http://www.orchidboard.com/community...me-garden.html
http://www.orchidboard.com/community...ht-levels.html
LED Lights
http://www.orchidboard.com/community...new-light.html
http://www.orchidboard.com/community...acts-pics.html
A summary thread on lighting
. Every time this topic comes up, I got into a meltdown, trying to sort through too many choices but this is FANTASTIC!!! I appreciate what you've done, here
This is just so helpful.
, NDL = 4200K, WDL = 3000K)
Linear Mode
