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**Phlkxkbh** · 08-23-2012, 12:48 AM

No. Red and blue light have differing effects on growth and flowering. It is generally believed that red light enhances flowering, blue light enhances vegetative growth. This is probably overly simplistic. White light (if it is 'true' white light - or something close) has both red and blue in it, as well as some wavelengths that plants don't really use (green) and some that are a bit more ambiguous as to their function. It seems that plants do pretty well with just red and blue, but there are cases where more wavelengths increase results.

When you see a 'red/blue' style grow light (I call them alien abduction lights), there is generally some ratio of red to blue. Most of the ones I use are about 2:1 red to blue. But I've seen 8:1 red to blue offered. Rarely do I see lights which have more blue than red.

So, for a terrarium (or vivarium), white light is probably best because you are going to be observing your plants (and/or animals) under that light. Other colors will weird you out. Unless you have them on separate switches (turn on white for viewing, color for plant growth).

Where the red and blue come in handy is for propagation or flowering. In theory (and I'm going to test it for orchids, really, someday) growing seedlings under blue light will give you compact growth with no unnecessary diversions into flowering. We all know some plants bloom too young... Then, switch to high red when the plants are of good size, and watch your blooms go boom. For general growth and flowering at the same time, then mix a couple reds with a blue. That part I know works, I get both good growth and flowering of adult plants under LEDs, I'm confident in that.

Penetration is generally a lot better with the LEDs, since they are directional and (often) focused with lenses. Even if not focused, you still get more penetration because all of the light is going in the same general direction. With a fluorescent tube, half of your light is going up, and bouncing back down if you have a reflector (possibly through the tube), you lose a lot of light that way. Without a reflector... well...

08-23-2012, 12:48 AM	#12
Phlkxkbh Join Date Oct 2005 Posts 406 Senior Member	No. Red and blue light have differing effects on growth and flowering. It is generally believed that red light enhances flowering, blue light enhances vegetative growth. This is probably overly simplistic. White light (if it is 'true' white light - or something close) has both red and blue in it, as well as some wavelengths that plants don't really use (green) and some that are a bit more ambiguous as to their function. It seems that plants do pretty well with just red and blue, but there are cases where more wavelengths increase results. When you see a 'red/blue' style grow light (I call them alien abduction lights), there is generally some ratio of red to blue. Most of the ones I use are about 2:1 red to blue. But I've seen 8:1 red to blue offered. Rarely do I see lights which have more blue than red. So, for a terrarium (or vivarium), white light is probably best because you are going to be observing your plants (and/or animals) under that light. Other colors will weird you out. Unless you have them on separate switches (turn on white for viewing, color for plant growth). Where the red and blue come in handy is for propagation or flowering. In theory (and I'm going to test it for orchids, really, someday) growing seedlings under blue light will give you compact growth with no unnecessary diversions into flowering. We all know some plants bloom too young... Then, switch to high red when the plants are of good size, and watch your blooms go boom. For general growth and flowering at the same time, then mix a couple reds with a blue. That part I know works, I get both good growth and flowering of adult plants under LEDs, I'm confident in that. Penetration is generally a lot better with the LEDs, since they are directional and (often) focused with lenses. Even if not focused, you still get more penetration because all of the light is going in the same general direction. With a fluorescent tube, half of your light is going up, and bouncing back down if you have a reflector (possibly through the tube), you lose a lot of light that way. Without a reflector... well...
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